(19)
Europaisches Patentamt
European Patent Office
Office europeen des brevets
(11)
EP 0 709 225 B1
(12)
EUROPEAN PATENT SPECIFICATION
(45) Date of publication and mention
of the grant of the patent:
05.08.1998 Bulletin 1998/32
(21) Application number: 95307663.5
(22) Date of filing: 27.10.1995
(51) Int. CI 6 : B41M5/28, B41M5/34
(54) Reversible multi-color thermal recording medium
Reversibles mehrfarbiges warmeempflindliches Aufzeichnungsmaterial
Materiau pour I'enregistrement thermique multicolore et reversible
(84) Designated Contracting States:
BE DE FRGBIT SE
(30) Priority: 27.10.1994 J P 262998/94
29.11.1994 JP 294142/94
(43) Date of publication of application:
01.05.1996 Bulletin 1996/18
(73) Proprietor:
NIPPON PAPER INDUSTRIES CO., LTD.
Kita-ku, Tokyo (JP)
(72) Inventors:
• Minami, Toshiaki,
c/o Res. Lab. of Product Dev.
1-chome, Shinjuku-ku, Tokyo 161 (JP)
• Nagai, Tomoaki,
c/o Res. Lab. of Product Dev.
1-chome, Shinjuku-ku, Tokyo 161 (JP)
• Hamada, Kaoru,
c/o Res. Lab. of Product Dev.
1-chome, Shinjuku-ku, Tokyo 161 (JP)
CO
LO
CM
CM
<T>
O
o
Q.
LU
• Sekine, Akio,
c/o Res. Lab. of Product Dev.
1-chome, Shinjuku-ku, Tokyo 161 (JP)
(74) Representative:
Woods, Geoffrey Corlett
J.A. KEMP & CO.
14 South Square
Gray's Inn
London WC1 R 5LX (GB)
(56) References cited:
EP-A- 0 530 699
US- A- 5 1 68 029
• PATENT ABSTRACTS OF JAPAN vol. 18 no. 383
(M-1640) ,19 July 1994 & JP-A-06 106844
(TOPPAN PRINTING COMPANY LIMITED) 19
April 1994,
• PATENT ABSTRACTS OF JAPAN vol. 18 no. 383
(M-1640) ,19 July 1994 & JP-A-06 106849
(MATSUSHITA ELECTRIC INDUSTRIAL
COMPANY LIMITED) 19 April 1994,
Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give
notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in
a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art.
99(1) European Patent Convention).
Printed by Xerox (UK) Business Services
2.16.3/3.4
EP 0 709 225 B1
Description
Background of the Invention
s This invention relates to a reversible multi-color thermal recording medium which is free from color development of
its ground when an image is formed or erased, has high sensitivity and provides a vivid color tone.
Thermal recording sheets are generally prepared by the following method. A colorless or pale basic achromatic dye
and an organic developer made from a phenolic substance or the like are ground into fine particles and dispersed, and
the resulting dispersions are mixed together. To the resultant mixture are added a binder, a filler, a sensitizer, a lubricant
10 and other auxiliaries to prepare a coating fluid. The coating fluid is applied to a support such as paper, synthetic paper,
film, plastic or the like to produce a thermal recording sheet. Color development recording is effected by an instantane-
ous chemical reaction caused by heating with a hot pen, a thermal head, a hot stamp, a laser beam or the like.
These thermal recording sheets are now applied in a wide range of fields such as measuring recorders, terminal
printers for computers, facsimiles, automatic ticket vending machines, bar code labels and the like. Along with recent
is progress in the diversification and the improvement of performance of these recording apparatuses, higher quality is
required for the thermal recording sheets. For instance, along with an increase in the speed of recording, the thermal
recording sheets are required to obtain high-density and clear color images with extremely small heat energy. Further,
the thermal recording sheets are required to be excellent in keeping quality such as light resistance, weather resistance
and oil resistance.
20 On the other hand, due to a sharp increase in the consumption of information recording media resulted by the con-
struction of a variety of networks and the popularization of facsimiles and copiers, waste disposal is becoming a social
problem. As one of solutions to this problem, much attention is paid to recording media having reversibility, that is, so-
called reversible recording media which allow for repetitions of recording and erasure.
The reversible recording media have been disclosed such as recording media in which a recording material
25 changes between transparent and opaque reversibly according to given temperature, recording media which make use
of reversibility of a thermochromic material, recording media which make use of reversible changes in the color tone of
a leuco dye, and the like.
The reversible recording media in which a recording material changes between transparent and opaque reversibly
are disclosed in Japanese Patent Publication Nos.54-1 19377, 63-39377, 63-41 1 86, 3-230993 and 4-366682. However,
30 these reversible recording media have such defects as lack of image sharpness, slow decolorization speed and need
for temperature control upon erasure.
The reversible recording media making use of a thermochromic material involve the problem that most of thermo-
chromic materials have poor data storage ability and require continuous heat supply to keep color development.
Meanwhile, the reversible recording media making use of reversible changes in the color tone of a leuco dye are
35 disclosed in Japanese Patent Publication Nos. 60-193691, 60-257289 and the like. However, these recording media
effect decolorization with water or steam and have problems with practical application. Further, Japanese Patent Pub-
lication Nos. 2-188293 and 2-188294 disclose a simple layer-structured material (color developing and subtracting
agent) which has both color developing and subtracting functions to provide reversible changes in the color tone of a
leuco dye only by controlling heat energy. However, with this color developing and subtracting agent, satisfactory color
40 density cannot be obtained because decolorization process already starts in process of color development. Further,
decolorization cannot be accomplished. For this reason, satisfactory image contrast cannot be obtained.
A heated roll which is controlled to a specific temperature is used to erase an image on a reversible recording
medium making use of reversible changes in the color tone of a leuco dye. Since a reversible developer used in the
reversible recording medium has no heat resistance, the ground of the medium markedly develops a color through
45 heated roll treatment.
As described above, the reversible recording media of the prior art which make use of a reaction between a color
coupler and a color developer involve various problems and are still unsatisfactory.
Meanwhile, there have been great needs for multi-color recording media, and double-color thermal recording paper
for use in labels, coupon tickets, video printers and the like has been implemented. This thermal recording paper is
so structured such that it is a laminate consisting of a support and high-temperature and low-temperature color developing
layers formed on the support which develop colors with different color developing energies and two different methods
have been proposed. One of them is to obtain a color of an image obtained when the high-temperature color developing
layer develops a color as an intermediate color between a color developed only by the high-temperature layer and a
color developed only by the low-temperature layer without discoloring an image of the low-temperature color-developing
55 layer which develops a color when the high-temperature color developing layer develops a color. In this case, a double-
color image having good contrast cannot be obtained unless a color developed by the high-temperature color develop-
ing layer can conceal a color developed by the high-temperature color developing layer thoroughly. It is impossible to
form a double-color image if a color developed by the low-temperature color developing layer is black.
2
EP 0 709 225 B1
The other method is to erase a colored image of the low-temperature color developing layer which develops a color
simultaneously with the color development of the high-temperature color developing layer, using an appropriate
decolorizing agent. In this case, combinations of developed colors are arbitrary. However, since compatibility between
color developing property and decolorization property is hard to be obtained, a satisfactory decolorization agent is yet
5 to be discovered.
Summary of the Invention
It is therefore an object of the invention to provide a reversible multi-color thermal recording medium which is free
10 from color development of its ground when an image is formed or erased, has high sensitivity, and provides a vivid color
tone.
This invention has been made to solve the above problems by using an irreversible heat-resistant color developer
as an organic color developer contained in an irreversible thermal composition and a reversible heat-resistant color
developer as an organic color developer contained in a reversible thermal composition in a reversible multi-color ther-
15 mal recording medium prepared by laminating the irreversible thermal composition containing a colorless or pale basic
achromatic dye and the organic color developer as main components and the reversible thermal composition containing
a colorless or pale basic achromatic dye and the organic developer as main components on a support.
In concrete terms, a compound represented by the following general formula (I) or (I*) is used as the reversible heat-
resistant color developer and at least one of compounds represented by the following general formulae (II), (III), (IV) and
20 (V) is used as the irreversible heat-resistant color developer.
30
O
II
R-NII-C-NH-< i-B-OIl
(1)
35
In the above formula (I), X is selected from the group consisting of a hydrogen atom, alkyl group having 1 to 12 car-
bon atoms, halogenated alkyl group having 1 to 3 carbon atoms, alkoxy group having 1 to 12 carbon atoms, alkoxycar-
bonyl group having 1 to 12 carbon atoms, acyl group having 1 to 12 carbon atoms, dialkylamino group having 1 to 12
40 carbon atoms, nitro group, cyano group and halogen atom, m is an integer of 1 to 12, and n is an integer of 1 to 3.
In the above formula (I'), R is an alkyl group having 12 to 22 carbon atoms, A is selected from the group consisting
of a lower alkyl group, lower alkoxy group, lower alkoxycarbonyl group, nitro group, halogen atom and hydrogen atom,
and n is an integer of 1 to 3.
45
x m -<s>-rrr<^>- so 2 - ni, 2 - ci °
II O LI
In the above formula, X is selected from the group consisting of a lower alkyl group having 1 to 4 carbon atoms,
alkoxy group having 1 to 3 carbon atoms, hydrogen atom, nitro group, cyano group and halogen atom, and m is an inte-
55 ger of 1 to 3.
3
EP 0 709 225 B1
II
-NH-C-NH-
X
S
II
0)-NH-C-Nll-
(III)
X
m
10
In the above formula, X, R1 , R2, R3, R4, R5, R6, R7 and R8 are independently selected from the group consisting
of a lower alkyl group having 1 to 6 carbon atoms, alkoxy group having 1 to 6 carbon atoms, hydrogen atom, nitro group,
is cyano group and halogen atom, and m is an integer of 1 to 3.
n
20
N H
O
II
C
o
Nil- (CIl 9 ) m
NH-C-NH-
(IV)
HO
OH
25
In the above formula, X is selected from the group consisting of a lower alkyl group having 1 to 6 carbon atoms,
alkoxy group having 1 to 6 carbon atoms, nitro group, halogen atom and hydrogen atom, m is an integer of 1 to 12, and
n is an integer of 1 or 2.
30
R
R
(V)
R
35
In the above formula, X is selected from the group consisting of an alkyl group having 1 to 12 carbon atoms, alkoxy
40 group having 1 to 12 carbon atoms, trihalogenated methyl group, hydrogen atom, nitro group and halogen atom, Z is
selected from the group consisting of O, S, straight chain having 1 to 12 carbon atoms, branched chain C-|-Ci 2 alkylene
group, NH, SO 2 and C=0, R1 , R2 and R3 are independently selected from the group consisting of an alkyl group hav-
ing 1 to 6 carbon atoms, hydrogen atom, nitro group and halogen atom, and n is an integer of 1 to 3.
As for erasure of an image on the reversible thermal recording medium, various methods are conceivable such as
45 one in which temperature and the amount of heat lower than those at the time of recording are given with a thermal
head, a hot stamp, a heated roll or the like for erasure, one in which the amount of light smaller than that at the time of
recording is irradiated by a laser, a halogen lamp or the like for erasure, and one in which the ground of a recording
medium is brought into contact with a low-boiling alcohol solvent such as methanol and ethanol for erasure. Particularly,
a heated roll controlled to 100 to 150 °C is easily used from a view point of operational ease. In this case, since the
so reversible recording composition and the irreversible recording composition are treated with a heated roll at the same
time, a heat-resistant color developer needs to be used to prevent both of the reversible recording composition and the
irreversible recording composition from developing colors from their grounds.
Further, as for the order of laminating the reversible recording composition and the irreversible recording composi-
tion onto a substrate, the substrate, the irreversible recording composition and the reversible recording composition may
55 be laminated in the order named, or the substrate, the reversible recording composition and the irreversible recording
composition may be laminated in the order named. Or two or more layers of the reversible recording composition and
the irreversible recording composition may be laminated together.
In the present invention, since the hue of an image obtained by first recording or erasure is made different from the
4
EP 0 709 225 B1
hue of an image recorded next by using a combination of the irreversible recording composition and the reversible
recording composition, it is possible to find whether an recorded image is additionally recorded or not.
Illustrative examples of the irreversible heat-resistant color developer used in combination with the leuco dye in the
reversible multi-color thermal recording medium of the present invention include the following urea compounds and
thiourea compounds. However, the color developer of the present invention is not limited to these.
<^-N--C--N--<Q>-S() 2 --NH 2 ( A1 )
I II I
H O H
C>> VS -?--<□> S °2 NI, 2
, > II I
CII (I O II
2 H 5 -<Q>-N-C-N-<jQ)-S0 2 " Nfl 2 <A3)
H () 1 1
-<^~N J-N-<0>-S0 2 -NH 2
H O H
0>-N-C-N-<Q)-S0 2 -NH 2
tert- C 4 H g II O H
I II I
H O II
c, -^>-v-s-f-<0>- s ° z - NH 2
C l II O H
(A4)
(A5)
(A7)
F -<^-^ji^-<0>-S0 2 --NH 2 (A 8 )
H O H
Bj-
0>-N-C-M-<Q>-S0 2 -NM 2 (A9)
II O II
Br ~>^""?"|f"'V''N^"" SW 2 (Ai0>
B t H O II
f-jf N ^"SOj -NH 2 (All)
ri o ft
EP 0 709 225 B1
C »3°-<Q>
- N - C - N
I II I
H O II
SO z -Nil
(A12)
2 !, 5°-<U
°2 N
N - C
I II
II O
N-C
E II
(i U
N
I
II
N
i
II
NC
S °2 NH 2
SU 2 NH 2
N-C
I II
H O
S0 2 -Nil
(A 13)
(AM)
(A 15)
S0 2 - Nil
N-C
I II
H O
N -
I
H
(A 16)
SO„ -Nil
N-C
I II
II O
N-
I
II
- C1I
(A17)
- SQ 2
"N-C
I II
H O
Nil
II
C I
(A 18)
S<? 2 -Nil
N-C
I II
H C)
IN l\
L / \
T-<0>- cl
H C 1
(A 19)
CQ
S0 2 -Nil
N-C
I II
II O
n r
II
(AZO)
Ol
so 2 -
N - C —
I II
II O
CA21)
EP 0 709 225 B1
S0 2 -NH 2
N - C - N -
I II I
II 0 M
S0 2 -NH 2
H O FI NO
' S °2 " NH Z
- C- N~<f )> CN
I II I V:
II 0 II
H O II
C I II O H
(A 22)
(A 23)
(A24)
"7 ~ if~Y"rrTi" so 2 nii 2
H O H
(0/-N-C -N^|- S 0 2 -NH 2 (A26)
O?-^-*! -rHl" so 2 - NH 2 (A27)
i n T TOT s ° ? - " NH a (A28)
C 1 II O H l - v - / - J
"rrrrfTi so 2 _nh 2 (az9>
H o H
"l "B'V'KTl " SW 2 " N "z (A3,))
f n o n ^^r^
EP 0 709 225 B1
g>-NII-£-NI.-<^-S^?5
s
II
N 1 1 - C - N 1 1
(B 1 )
S
^)-NM-C-NFI-^3V S '^C^ NH - " " N,l ~<^^ (B2)
C 1
C I
o>-
s
II
NH-C-NII-
s
II
NH-C-NH
-<§>
(B3)
CI CI
S
Q^) - N 1 1 - C - N 1 1 ~^0)^ S XO)^ N [ 1 ~ " ~ NM
(BO
CI CI CI CI
S
II
s
II
Br Br
S
S
II
(O)- N H - C - N (I ~(C^ s ~^C^" N II — C - N H ~<(0)
(B6)
Mc Mc
Me=-CII
3
NII-C-N H
S
II
Nil-C-NII-
(B7)
tert- C, II n
4 y
tert- C. II n
4 y
8
EP 0 709 225 B1
S
s
C I -
{O)- N I I - C - N 1 1 -^Q^" S ~\0)~ N II - C — N 1 1 -(O/* - C
(I3 8)
S
C I
N II — C - Nil -^Q/~ s ^'^}" N n ~ " - N H -<^Q^> C
C I
C I
(I3 9)
S
c i -/QVnu-c-nii-cQVs-/ (_)Vnii-c-nii-(QVc i
s
II
c I
c I
(BIO)
C I
C I -
C I
s
II
C l
- N I f — C — N 1 1 -^O)- S
N
ii-c-n n-<(Q/
c i
c I
(BID
S
II
Qy>~ N II — C — N I I -^Q^~ S
NII-C-N
(BI2)
F
C II
3
S
II
-^Q^~ N H - C — NM-^Q^- s "^Q^~ N " ~ C ~ N H XO
CH
(B13)
Cll
3 V
S
II
cn 3 -/q)- nh-c-n h XO)' s -< \C ^n'^c-n"
C 111 ~ ( 13 14) Cll
C II
3
C II
3
EP 0 709 225 B1
C I C I s
CI CI
S 13 r
Nil - C - Nil <(0/ S -(O)"" N 1 1 - C - N 1 1 -<^Q) ( 13 16)
B r
S C IF S
N 11 - C - N II -^Q^- S -^Q^>- NII-C — NH-^Q^-n-C^ M
13
C 2 M 5 (B 17)
S C II „ S
Q^>- N H — C — N 1 1 s ~^Q^~ N II - C - N H ~<(0/ > " N °2
CII 3 (B18)
S CM„ / C1, 3 S
N 1 1 — C — N I I -\^y~ S -^Q/~ N 1 1 - C - N H -<^0)~ C N
c n 3 !^ c n 3 (B19)
S CII„ ,C I s
<^Q)- NH-C-NI! S "{0/~ N M - C - N II -{Q) ( '320)
c u 3 V.I
(Q)- N M — C — NII -^Q^- s ~(0)~ N 1 1 - C - N 1 1 ~(0) ( B 21 )
CM Cll CII 3 C 1
10
EP 0 709 225 B1
11
EP 0 709 225 B1
o
II
N II — C — N II —
(Cii 2 ) 8
-Nil
C = 0
I
N II
M e
O
1 1 O -\^y~ N H — C — N 1 1
(C,, 2 ) 6
M e = Methyl
!IO
M e
Nil
I
C-0
I
Nil
ii
NH-C-Nll - CC II „ ) .
Nil
R . = tert-Butyl
noTo
c = o
I
Nil
Rz >"\
ii0 "\O/ _NM
o
II
-C-NII- (CH 2 ) G
R =n-lle.\yl
Nil
I
C = 0
I
Nil
(C 7)
(C 8)
(C 9)
(CIO)
12
EP 0 709 225 B1
Me °^Cy NH-C-NH- (cn z ) G -Nil (CU)
I
c = o
M e =MeUiyl A^T\ I
MeO-^Q)-NII
10
* on
I I Ox o
r5
20
35
l l W\ v./
MeO-<^Q^~NH-C-NH- (Cllg ) g "Nil (C12)
C = 0
Me=Kethyl 1
Me 0-< (J) V Nil
110
25 II Ox O
1 1 v/\
R 3 0\Q\-NU-C-NU- (CH 2 ) B -Nil (C13)
C = 0
30 R =n-ButyI
R, 0-(O)" Nn
3
no
UOs o
R 2 O-^^-NII-C-NII- (CM 2 ) g -Nil (CM)
40 C = 0
R„ =n Hexyl I
2 R 9 °-(0)- NI1
2
II O
45
50
55
13
EP 0 709 225 B1
on o o no-
li II
O N' 'NO
2
14
EP 0 709 225 B1
OH O
II
O HO
C l-< Q/-NU-C-NII- (CII 2 ) g -
C f
Nn-C-NIl-<^^^-
C I
C 1
II Ov
o
Me
NH-C-NH- (CII„ ) .
M e =-Methyl
O /O
- N II — C — N H -^Q/~
OH
M e
Me
McO
\
H0-<O
McO
O
II
NH-C
Nil- (cn 2 ) [2 -Nil
M e O
McO
15
EP 0 709 225 B1
O
— N H — C — N M — < ( ) >- O
O
II
C H 3 ~<(0)- N l-l — C — N H <^>- O
O
II
<S>-NH-C-NH-<0>-0
CH,
J O
II
-NH-C-NH ~^Q) _ 0
R
R = tert- C. H n
o
c 12 H Z5-(0)- NH - C - NH -(0)-°
,CH 3 O
O-NH-C-NII-<@>-0
CH
3
O
II
CM 0-<^Q>-NH-C-NH-<£))-6
O
II
12
H 25° _< 0)~ N H - C - N I I -<Q)- O
16
EP 0 709 225 B1
(DID
O
^_ NH -5^NH-<S>-0-<0> (DIZ)
O
n>- NH -!- NH -<o>-o-<o
ci
CI o
0>-NH-£-NH-<g>-0-<0
CI
(D13)
(D 14)
Ql O
-^>-NH-C-NM-<g>-0-<g> (D15)
(D16)
II < Z H 3
O>-NH-C-NH-<5>-0-<O>-CI (D17)
O
-<g>_MH-C-NH-<Q>-0-<0)-NO. (DJ8)
\ / \ f £_
o
-<Q)-NH-C-NH-<g>-0-<g> (D19)
O
-<Q^- N H - C - N H -<Q>- O -<^> (D20)
C I
17
EP 0 709 225 B1
O
<^Q)-NH-C-NII (DZ3)
-G-<( )>-n-C 6 H„
O
II
<?2))-NII-C-NM (DZ4)
o
II
<g>_ NH-C-NH -<g>- S -<g> ( D 25)
O
n
0-NH-C-NH-(g)-CH 2 -<^> (D26)
O
H
<Q>-NH-C-NH-<^)-NM-(0) (D27)
0
'0>-NH-C-NH-<^0)-SO, -<S) (D28)
O
II
<^)_ NH -i-NH-<^>-C-<g> (D29)
II
0
In the reversible multi-color thermal recording medium of the present invention, illustrative examples of the revers
ible thermal developer used in combination with the leuco dye include the following compounds represented by the gen
eral formula (I), but it is not limited to these.
18
EP 0 709 225 B1
o o
Q^-NH-C-NH-CH 2 -NH-C-NH-<^Q) (El)
O O
II II
(^-NII-C-NII- (Cll 2 ) 2 -NII-C-NH-^O/ (E2)
O O
II II
Q^-NH-C-NII- (CH 2 ) 3 -Nll-C-NH-^O/ (E3)
O O
^^-NH-C-NII- (CII 2 ) 4 NII-C-NM-^O) (E4)
O O
Q^-NH-C-NH- (CH 2 ) 5 -NII-C-NH-^Q) (E 5)
O 0
^-NU-C-NH- < < CU 2 ) G - N[| -C-NII-<Q) (E6)
o o
Qy NH-C-NH- (CH 2 ) ? -NH-C-Nn-<JO) (E7)
0 O
II
QVnII-C-NII - (CH 2 ) 8 -NM-C-NH-/0
19
(E 8)
EP 0 709 225 B1
O O
ll
Nll-C-Nll- CCIl 2 ) g - NN-C-Nll-<0) (K9)
o o
VnH-C-NH- CCII z ) jg-Nll-C-NII-^Q/ (E10)
O O
\nII-C-NH- ( - C[] 2 ) 11 -NM-C-NH-<^^ (Ell)
o o
^-NII-C-NU- CC II 2 ) ]2 -NH-C-NH-^Cy (E12)
O O
-^Q^-NH-C-NII- (CU 2 ) 6 -Nll-C-NlI-<^Q)-Me
Me=-Methyl CE13)
e N O O /Me
>—\ II II
\OX Nn ~ C ~ NI1 " (Cl, 2 G " Nn - c - NI1
Me=-Iethyl (EH)
O O
II H
•^^-NH-C-NH- (CH 2 ) 6 -NII-C-NH-^O/ E t
li t =-Ethyl (E15)
O O
NH-C-NII- (Cll 2 ) 6 -NH-C-NH-^Q^-R (E16)
R=-n-C |2 ll z5
20
EP 0 709 225 B1
McO\ O O ,OMe
^Q^-N1I-C-NH- (CU 2 ) 6 -NII-C-NIl^Q
Me=-»eUiyl (El7)
O O
RO-<^Q)-Ntl-C-NH- CC II 2 ) 6 -NII-C-NH-<(^3)^ OR
R= -tert-Butyl (EI8)
O O
R0 ~^Cy~ NII-C-NII- (CU 2 ) 6 -Nli-C-NH-<^Qy OR
R--n-C 1() H 2l (E19)
O O
RO-^Q)-NH-C-NtI- (CII 2 ) 6 -NII-C-NU-(^Q^-OR
R = -n-C 1 „lI,, r (E20)
O O
Me 2 N-<^Q^-NH-C-NH- (CU 2 ) G N H - C - N H -<^Q^-NM e
2
Me=-Methyl (E21)
O O
E t 2 N-<^Qy-NII-C-NII- (CII 2 ) 6 NH-C-Nt[-<^Qy-NE t
2
E t =-F.l.hyl (E22)
C I -<^Q^)-NH-C-NH
O O
II
(CIL ) r -NH-C-NH
Z b
(E23)
C l x O O /CI
<^Q^-NII-C-NI1- (CH 2 ) 6 -NI1-C-NH-<^Q^ CE24)
21
EP 0 709 225 B1
O O
QV NH-C-NH- (CII 2 ) 6 -NII-C-NH-^Q) (E25)
CI CI
o o
r
(E26)
13 r -<^Q^)- N H - C — N II — (C II 2 ) g - N II - C - N II ^(Cy B
O O
II II
F-<( )>-NH-C-NlI- (CH 2 ) - -NII-C-NH-<( )>- F (E27)
O O
°2 N NH-C-NH- (CH 2 ) 6 NH-C-NH-^Q^-NO z
(E28)
0 0 0 0
Me OC-^Q^-NH-C-NII- (CII 2 ) g -NH-C-NH-^Q^-COMe
Me=-Methyl (E29)
0 0 0 0
ROC^Oy NII-C-NH- (CII 2 ) 6 -NH-C-NH C0R
R=-n- C 12 II 25 (E30)
0 0
^QN-NM-C-NH- (CH 2 ) B -NH-C-NH-^Q^ (E31)
C=N N=C
o o
M c -^0^~ NH-C-NH- (Cll 2 ) 4 - -NIl-C-NH-^-Me
Me=-«etliyl (E32)
22
EP 0 709 225 B1
Mc N O O /Me
II H
0/-NII-C-NH- CCM ) -NII-C-NH-^O) (E33)
2 ' \
M e = -Methyl
0 O
Me-<^^NU-C-NH- (CI, 2 } 8 - N "- c - Nf, XO/^ Me
Me=-Methyl (E34)
Me x O O /Me
(E35)
M e = Methyl
O O
II II
R t -<T^NH-C-NII- (C[I 2 } l0 -N"-C-NII-<Q)~ E t
E t =-EthyI (E36)
O O
c i -<^Q^-nh-c-nh- (cn 2 ) g nii-c-nh-{qVc 1
CI CI (E37)
M e
Mc=-Methyl (E38)
MeO^ O O /OMe
NII-C-NII- (CH 2 ) G -NII-C-NH-(O/~ 0Me
Me=-Kelhyl (E39) OMe
RO
/OR O O RO x
-<^Q)-NU-C-N[I- CCiI 2 ) A -NH-C-NII-^^-OR
R=--iso-C 3 H ? (E40)
In the reversible multi-color thermal recording medium of the present invention, illustrative examples of the revers-
ible heat-resistant color developer used in combination with the leuco dye include the following compounds represented
by the general formula (I')-
N-octadecyl-N'-(4-hydroxyphenyl)urea (E1 ')
23
EP 0 709 225 B1
N-octadecyl-N'-(3-hydroxyphenyl)urea (E2')
N-octadecyl-N'-(2-hydroxyphenyl)urea (E3')
N-octadecyl-N'-(4-hydroxy-2-methylphenyl)urea (E4')
N-octadecyl-N'-(2-hydroxy-4-methylphenyl)urea (E5')
N-octadecyl-N'-(4-hydroxy-2-nitrophenyl)urea (E6')
N-odtadecyl-N'-(4-hydroxy-3-nitrophenyl)urea (E7')
N-octadecyl-N'-(3-hydroxy-4-methoxyphenyl)urea (E8')
N-octadecyl-N'-(5-hydroxy-2-methoxyphenyl)urea (E9')
N-octadecyl-N'-(4-chloro-2-hydroxyphenyl)urea (E10')
N-octadecyl-N'-(3-chloro-4-hydroxy-5-methylphenyl)urea (E1 1')
N-octadecyl-N'-(3,5-dichloro-4-hydroxyphenyl)urea (E1 2')
N-octadecyl-N'-(3,5-dibromo-4-hydroxyphenyl)urea (E1 3')
N-dodecyl-N'-(4-hydroxyphenyl)urea (E1 4')
N-dodecyl-N'-(3-hydroxyphenyl)urea (E15')
N-dodecyl-N'-(2-hydroxyphenyl)urea (E16')
N-dodecyl-N'-(4-hydroxy-2-methylphenyl)urea (El 7')
N-dodecyl-N'-(4-hydroxy-3-nitrophenyl)urea (E1 8')
N-dodecyl-N'-(3-hydroxy-4-methoxyphenyl)urea (E1 9')
N-dodecyl-N'-(3-chloro-4-hydroxy-5-methylphenyl)urea (E20')
N-dodecyl-N'-(3,5-dichloro-4-hydroxyphenyl)urea (E21 ')
N-tetradecyl-N'-(4-hydroxyphenyl)urea (E22')
N-tetradecyl-N'-(3-hydroxyphenyl)urea (E23')
N-tetradecyl-N'-(2-hydroxyphenyl)urea (E24')
N-tetradecyl-N'-(4-hydroxy-2-methylphenyl)urea (E25')
N-tetradecyl-N'-(4-hydroxy-2-nitrophenyl)urea (E26')
N-tetradecyl-N'-(5-hydroxy-2-methoxyphenyl)urea (E27)
N-tetradecyl-N'-(3,5-dibromo-4-hydroxyphenyl)urea (E28')
N-hexadecyl-N'-(4-hydroxyphenyl)urea (E29')
N-hexadecyl-N'-(3-hydroxyphenyl)urea (E30')
N-hexadecyl-N'-(2-hydroxyphenyl)urea (E3V)
N-hexadecyl-N'-(4-hydroxy-2-methylphenyl)urea (E32')
N-hexadecyl-N'-(4-hydroxy-2-nitrophenyl)urea (E33')
N-hexadecyl-N'-(5-hydroxy-2-methoxyphenyl)urea (E34')
N-hexadecyl-N'-(4-chloro-2-hydroxyphenyl)urea (E35')
N-hexadecyl-N'-(3-chloro-4-hydroxy-5-methylphenyl)urea (E36')
N-eicosyl-N'-(4-hydroxyphenyl)urea (E37')
N-eicosyl-N'-(3-hydroxyphenyl)urea (E38')
N-eicosyl-N'-(2-hydroxyphenyl)urea (E39')
N-eicosyl-N'-(4-hydroxy-2-methylphenyl)urea (E40')
N-eicosyl-N'-(4-hydroxy-2-nitrophenyl)urea (E41 ')
N-eicosyl-N'-(5-hydroxy-2-methoxyphenyl)urea (E42')
N-eicosyl-N'-(4-chloro-2-hydroxyphenyl)urea (E43')
N-eicosyl-N'-(3-chloro-4-hydroxy-5-methylphenyl)urea (E44')
In the reversible multi-color thermal recording medium of the present invention, the basic achromatic dye used in
combination with the heat-resistant color developer is not limited to a particular kind, but triphenyl methane, fluoran, f lu-
orene and divinyl-based dyes are preferred. Specific examples of these dyes are shown below. These dyes may be
used alone or in combination of two or more.
(triphenylmethane-based leuco dyes)
3,3-bis(p-dimethylaminophenyl)-6-dimethylamino phthalide [another name is crystal violet lactone]
(fluoran-based leuco dyes (I))
3-diethylamino-6-methyl-7-anilinofluoran
3-(N-ethyl-p-toluidino)-6-methyl-7-anilinofluoran
3-(N-ethyl-N-isoamylamino)-6-methyl-7-anilinofluoran
24
EP 0 709 225 B1
3-diethylamino-6-methyl-7-(o,p-diiTiethylanilino)fluoran
3-pyrrolidino-6-methyl-7-anilinofluoran
3-piperidino-6-methyl-7-anilinofluoran
3-(N-cyclohexyl-N-methylamino)-6-methyl-7-anilinofluoran
3-diethylamino-7-(m-trifluoromethylanilino)fluoran
3-N-n-dibutylamino-6-methyl-7-anilinofluoran
3-N-n-dibutylamino-7-(o-chloroanilino)fluoran
3-(N-ethyl-N-tetrahydrofurfurylamino)-6-methyl-7-anilinofluoran
3-dibutylamino-6-methyl-7-(o,p-dimethylanilino)fluoran
3-(N-methyl-N-propylamino)-6-methyl-7-anilinofluoran
3-diethylamino-6-chloro-7-anilinofluoran
3-dibutylamino-7-(o-chloroanilino)fluoran
3-diethylamino-7-(o-chloroanilino)fluoran
3-diethylamino-6-methyl-chlorofluoran
3-diethylamino-6-methyl-fluoran
3-cyclohexylamino-6-chlorofluoran
3-diethylamino-benzo[a]-fluoran
3-n-dipentylamino-6-methyl-7-anilinofluoran
2-(4-oxo-hexyl)-3-dimethylamino-6-methyl-7-anilinofluoran
2-(4-oxo-hexyl)-3-diethylamino-6-methyl-7-anilinofluoran
2-(4-oxo-hexyl)-3-dipropylamino-6-rnethyl-7-anilinofluoran
(fluorene-based leuco dyes)
3 l 6,6'-tris(dimethylamino)spiro[fluorene-9,3'-phthalide]
3,6,6'-tris(diethylamino)spiro[fluorene-9,3'-phthalide]
(fluoran-based leuco dyes (II) )
2-methyl-6-p-(p-dimethylaminophenyl)arninoanilinofluoran
2-methoxy-6-p<p-dimethylaminophenyl)aminoanilinofluoran
2-chloro-3-methyl-6-p-(p-phenylaminophenyl)aminoanilinofluoran
2-chloro-6-p-(p-dimethylaminophenyl)arninoanilinofluoran
2-nitro-6-p-(p-diethylaminophenyl)aminoanilinofluoran
2-amino-6-p-(p-diethylaminophenyl)aminoanilinofluoran
2-diethylamino-6-p-(p-diethylaminophenyl)aminoanilinofluoran
2-phenyl-6-methyl-6-p-(p-phenylaminophenyl)aminoanilinofluoran
2-benzyl-6-p-(p-phenylaminophenyl)aminoanilinofluoran
2- hydroxy-6-p-(p-phenylaminophenyl)aminoanilinofluoran
3- methyl-6-p-(p-dimethylaminophenyl)arninoanilinofluoran
3-diethylamino-6-p-(p-diethylaminophenyl)aminoanilinofluoran
3-diethylamino-6-p-(p-dibutylaminophenyl)aminoanilinofluoran
(divinyl-based leuco dyes)
3,3-bis-[2-(pdimethylaminophenyl)-2-(p-methoxyphenyl)ethenyl]-4,5,^
3,3-bis-[2-(p<iimethylaminophenyl)-2-(p-meth^
3,3-bis-[1 ,1-bis(4-pyrrolidinophenyl)ethylene-2-yl]-4,5,6,7-tetrabromophthalide
3,3-bis-[1^4-methoxyphenyl)-1-(4-pyrrolidinophenyl)ethylene-2-yl]-4,5,67-tetra^
(Others)
1,1-bis-[2\2\2'\2 M -tetrakis-(p-dimethylaminophenyl)ethenyl]-2,2-dinitrileethan
1 J-bis-[2\2\2'\2 M -tetrakis^p-dimethylam
1,1-bis-[2\2\2'\2 M -tetrakis-(p-dimethylaminophenyl)ethenyl]-2,2-diacetylethan
bis-[2,2,2\2'-tetrakis-(p-dimethylaminophenyl)-ethenyl]methyl malonate dimethyl
In the present invention, as a sensitizer, an aliphatic amide such as stearamide or palmitamide, ethylene bisamide,
25
EP 0 709 225 B1
montan wax, polyethylene wax, dibenzyl terephthalate, p-benzyl oxybenzyl benzoate, di-p-tolylcarbonate, p-benzyl
biphenyl, phenyl a-naphthyl carbonate, 1,4-diethoxy naphthalene, phenyl 1-hydroxy-2-naphthoate, 1 ,2-di-(3-methyl-
phenoxy)ethane, di(p-methylbenzyl)oxalate, p-benzyloxynaphthalene, 4-biphenyl-p-tolylether, 0-xylylene-bis-(phe-
nylether), 4-(m-methylphenoxymethyl)biphenyl or the like may be added within the range that does not impair the effect
of the invention.
In the present invention, when a plurality of reversible thermal recording layers and irreversible thermal recording
layers are provided to prepare a multi-color recording medium, an intermediate layer of a resin is preferably interposed
between the recording layers to be laminated together. The resin intermediate layer is intended to prevent the recording
layers from being mixed together during heating and can be formed by applying a resin which does not melt at a record-
ing temperature to the recording layers to be laminated together. The resin usable in the present invention may be of
the same kind as a binder resin used in adjacent recording layers, but is preferably incompatible with the binder resin.
Illustrative examples of the resin include polyvinylalcohol, polyacrylamide, polyacrylate and polyamide resins and the
like, but the resin is not limited to these. A multi-color thermal recording medium providing a vivid color tone can be
obtained by providing a resin intermediate layer.
The resin intermediate layer may be thick enough not to be broken by application of heat and pressure due to rep-
etitions of recording and erasure. If the resin intermediate layer is too thick, thermal conductivity deteriorates. Therefore,
the thickness of the intermediate layer is preferably as small as possible and typically 10 jam or less.
The intermediate layer of the present invention may contain a filler. The filler used in the invention may be an
organic or inorganic filler such as silica, calcium carbonate, kaolin, calcined kaolin, diatomaceous earth, talc, titanium
oxide or aluminum hydroxide. The weight ratio of the filler to the resin both constituting the intermediate layer is prefer-
ably 2:1 to 20:1.
Illustrative examples of the binder used in the reversible thermal recording layer and the irreversible thermal record-
ing layer of the present invention include denatured polyvinyl alcohols such as wholly saponified polyvinyl alcohols hav-
ing a polymerization degree of 200 to 1 ,900, partly saponified polyvinyl alcohols, carboxy-denatured polyvinyl alcohols,
amide-denatured polyvinyl alcohols, sulfonic acid-denatured polyvinyl alcohols, butyral-denatured polyvinyl alcohols
and other denatured polyvinyl alcohols, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, styrene-
maleic anhydride copolymer, styrene-butadiene copolymer and cellulose derivatives such as ethyl cellulose and acetyl
cellulose, polyvinyl chloride, polyvinyl acetate, polyacrylamide, polyacrylate, polyvinyl butyral, polystyrene and copoly-
mers thereof, polyamide resins, silicon resins, petroleum resins, terpene resins, ketone resins and cumarone resins.
These high molecular substances may be dissolved in a solvent such as water, alcohol, ketone, ester or hydrocarbon,
emulsified in water or other solvent, or dispersed like a paste, and may be combined in accordance with required quality.
The filler used in the reversible thermal recording layer and the irreversible thermal recording layer of the present
invention may be an organic or inorganic filler such as silica, calcium carbonate, kaolin, calcined kaolin, diatomaceous
earth, talc, titanium oxide and aluminum hydroxide.
In addition to these, a release agent such as an aliphatic acid metal salt, a lubricant such as wax, a water-proof
agent such as glyoxal, a dispersant, an anti-foaming agent and the like can be contained in the recording layers.
Further, an overcoat layer of a high molecular substance containing a filler may be formed on a thermal color devel-
oping layer for the purpose of improving keeping quality.
Moreover, an undercoat layer containing an organic or inorganic filler may be formed under the thermal color devel-
oping layer for the purpose of improving keeping quality and sensitivity.
The above organic color developer, basic achromatic dye and materials added as required are ground with a
grinder such as a ball mill, attritor or sand grinder or an appropriate emulsifier until a particle diameter of 1 jam or less
is achieved. The resulting particles are mixed with a binder and various additives according to application purpose to
prepare a coating fluid.
The amounts of the organic color developer and the basic achromatic dye used in the present invention and the
kinds and amounts of other components are determined according to required performance and recording quality and
not limited particularly Typically, 1 to 8 parts of the organic color developer and 1 to 20 parts of the filler are used based
on 1 part of the basic achromatic dye and 10 to 25% of the binder is used based on the total solid content.
To fabricate the reversible multi-color thermal recording medium of the present invention, the thermal coating fluid
and the intermediate layer coating fluid having the above compositions are applied alternately to a desired substrate
such as paper, synthetic paper, plastic film or nonwoven fabric and dried to prepare a multi-layered laminate. In this way,
the reversible multi-color thermal recording medium of interest can be obtained.
A light absorbent which absorbs light with its thermal recording layer or the like and converts it into heat can be con-
tained in the reversible multi-color thermal recording medium of the present invention to produce an optical recording
medium. The light absorbent used in the recording medium of the present invention to convert light into heat may be
any kind of substance provided it absorbs the wavelength of light coming from diverse light sources. Various dyes, var-
ious pigments, near infrared light absorbents may be used as the light absorbent of the present invention. However, the
light absorbent of the present invention is not particularly limited.
26
EP 0 709 225 B1
When a strobe having a continuous light wavelength is used as a recording light source, for example, a product
obtained from a heat reaction between a thiourea derivative and a copper compound as disclosed in Japanese Patent
Publication No. 2-206583 and the specification of JP-A-5-30954, graphite, copper sulfide, lead sulfide, molybdenum tri-
sulfide, black titanium and the like as disclosed in Japanese Patent Publication No. 3-86580 may be used as the light
absorbent which converts light into heat. In addition to these, carbon black may be used as the light absorbent. These
light absorbents may also be used as light absorbents for laser recording.
When a semiconductor laser which is excellent in terms of size, safety, price and modulation is used as a recording
laser, particularly when a semiconductor laser having an oscillation wavelength in visible to near infrared ranges is
used, examples of a material which absorbs such an oscillation wavelength include polymethine dyes (cyanine dyes),
azulenium dyes, pyrylium dyes, thiopyrylium dyes, squalenium dyes, croconium dyes, dithiol metal complex salt dyes,
mercaptophenol metal complex dyes, mercaptonaphthol metal complex dyes, phthalocyanine dyes, naphthalocyanine
dyes, triallyl methane dyes, immonium dyes, diimmonium dyes, naphthoquinone dyes, anthraquinone dyes, metal com-
plex salt dyes and the like as disclosed in JP-A-54-4142, JP-A-58-94494, JP-A-58-209594, JP-A-2-217287, Japanese
Patent Publication No. 3-73814, "Near Infrared Absorbing Dyes" (Chemical Industry No. 43 issued in May 1986) and the
like.
Illustrative examples of the polymethine dyes (cyanine dyes) include Indocyanine Green (manufactured of Daiichi
Pharmaceutical Co.), NK-20 14 (manufactured by Nippon Kanko Shikiso Kenkyujo Co.), NK-261 2 (manufactured by Nip-
pon Kanko Shikiso Kenkyujo Co.), 1,1,5,5-tetrakis(p-dimethylaminophenyl)-3-methoxy-1,4-pentadiene, 1,1,5,5-tet-
rakis(p-diethylaminophenyl)-3-methoxy-1,4-pentadiene and the like. Examples of the squalenium dyes include NK-
2772 (manufactured by Nippon Kanko Shikiso Kenkyujo Co.) and the like. Examples of the dithiol metal complex salt
dyes include toluene dithiol nickel complex, 4-tert-butyl-1 ,2-benzene dithiol nickel complex, bisdithiobenzyl nickel com-
plex, PA-1005 (manufactured by Mitsui Toatsu Senryo Co.), PA-1006 (manufactured by Mitsui Toatsu Senryo Co.),
bis(4-ethyldithiobenzyl) nickel complex disclosed in the specification of JP-A-4-80646, bis(4-n-propyldithiobenzy)nickel
complex and the like. Examples of the immonium dyes and the diimmonium dyes include IRG002 (manufactured by
Nippon Kayaku Co.), IRG022 (manufactured by Nippon Kayaku Co.) and the like. Examples of the naphthalocyanine
dyes include NIR-4 (manufactured by Yamamoto Kasei Co.), NIR-14 (manufactured by Yamamoto Kasei Co.) and the
like. Examples of the anthraquinone coloring matters include IR-750 (manufactured by Nippon Kayaku Co.) and the like.
These light absorbents may be used alone or in combination of two or more.
The light absorbent used in the optical recording medium of the present invention may be simply mixed with mate-
rials required to produce the optical recording medium. However, as disclosed in Japanese Patent Publication No. 2-
217287, the light absorbent is molten and mixed with materials of the light recording medium of the present invention
to be dissolved or dispersed in the materials. The materials to be mixed with the light absorbent which is dissolved or
dispersed therein include a sensitizer for thermal recording, the color developer of the present invention, a conventional
color developer, a dye precursor, a composition comprising a sensitizer for thermal recording and the color developer
of the present invention, a composition comprising a sensitizer for thermal recording and a conventional color devel-
oper, a composition comprising a sensitizer for thermal recording and a dye precursor, and the like.
As for the light absorbent used in the optical recording medium of the present invention, the materials of the optical
recording medium of the present invention and the light absorbent are dissolved or dispersed in a solvent in advance,
and a mixture of the dissolved or dispersed materials and light absorbent are separated from the solvent for use. The
materials which are dissolved or dispersed in the solvent together with the light absorbent are the same as the above
materials to be mixed with the light absorbent which is dissolved or dispersed therein.
Further, the light absorbent used in the optical recording medium of the present invention may be co-dispersed
(simultaneous mixing and dispersion) with any one of a dye precursor, a color developer and a sensitizer. The light
absorbent may also be co-dispersed (simultaneous mixing and dispersion) with a combination of a dye precursor and
a sensitizer or a combination of a color developer and a sensitizer.
The light absorbent used in the optical recording medium of the present invention or the light absorbent which is
subjected to any one of treatments such as heat-fusion with the above materials, mixing with a solvent and co-disper-
sion (simultaneous mixing and dispersion) is mixed with thermal recording materials consisting of the color developer
of the present invention and a dye precursor as a constituent material of a light absorptive thermal recording layer. The
light absorbent may be used as a material for constituting either upper or lower light absorptive layer formed on the ther-
mal recording layer made from the color developer of the present invention and the dye precursor. Further, the light
absorbent may be used as a material for constituting both upper and lower light absorptive layers formed on both sides
of the thermal recording layer. The light absorbent may be internally added to or impregnated into a support as a mate-
rial for constituting the light absorptive substrate. On top of this light absorptive substrate, the above thermal recording
layer or the above light absorptive thermal recording layer may be formed. The thermal recording layer or the light
absorbtive thermal recording layer on the light absorptive substrate may be multi -layer structured.
The amounts of the color developer and the dye precursor used in the reversible multi-color optical recording
medium of the present invention and the types and amounts of other components are determined according to required
27
EP 0 709 225 B1
performance and recording quality, and are not particularly limited. Typically, 1 to 8 parts of an organic color developer
and 1 to 20 parts of a filler are used based on 1 part of the dye precursor and a binder is contained in an amount of 1 0
to 25% of the total solid content. The amount of the light absorbent added is determined according to its light absorption
power.
Further, in the reversible multi-color optical recording medium of the present invention, like the thermal recording
medium of the present invention, an overcoat layer of a high molecular substance or the like may be formed on the
recording layer of the optical recording medium, or an undercoat layer containing an organic or inorganic filler may be
interposed between the recording layer and the substrate for the purpose of improving keeping quality and sensitivity.
The above light absorbent may be added to these overcoat layer and the undercoat layer.
The light absorbent as described above is ground with a grinder such as a ball mill, attritor and sand grinder or an
appropriate emulsif ier until a particle diameter of 1 jim or less is achieved and mixed with a binder and various additives
according to application purpose to prepare a coating fluid.
As the light source for recording on the optical recording medium of the present invention with light, a variety of
lasers such as semiconductor lasers and semiconductor excited YAG lasers, a xenon flash lamp, a halogen lamp and
the like may be used. Light irradiated from these light sources may be converged with a light converging means such
as a lens for optical recording on the optical recording medium of the present invention. Further, a mirror or the like may
be used to carry out optical scanning recording.
Since the reversible multi-color thermal recording medium and reversible multi-color optical recording medium of
the present invention have excellent heat resistance and extremely high thermal stability of its background color, a pow-
erful protective film can be provided by thermal lamination of a plastic film. Therefore, either before or after recording
with heat or light, it is possible to easily produce a card having heat resistance and various stabilities, which is protected
with a plastic film by means of a film for thermal lamination and a commercial laminator. Particularly, in the case of the
optical recording medium of the present invention, additional recording with light can be made on a laminated plastic
film. Illustrative examples of the plastic film for thermal lamination include thermoplastic resins such as low-density pol-
yethylene, ethylene-vinyl acetate copolymer (EVA), ethylene- ethyl acrylate copolymer (EEA), ethylene- methyl methacr-
ylate copolymer (EMAA) and ethylene-methacrylate copolymer (EMAA).
Further, extrusion coating is also possible for the reversible multi-color thermal recording medium and reversible
multi-color optical recording medium of the present invention, using an extrusion coating resin such as low-density pol-
yethylene which can be extruded at relatively low temperatures.
Moreover, since the reversible multi-color thermal recording medium and reversible multi-color optical recording
medium of the present invention is excellent in heat resistance, the grounds of these media do not develop colors even
if they contact a toner heat-fixing unit of an electronic photocopier. Therefore, these media can also be used as paper
for electronic photocopiers. Thermal recording or optical recording is possible either before or after toner recording with
an electronic photocopier.
A description is subsequently given of the mechanisms of color development and decolorization of the reversible
multi-color thermal recording medium of the present invention. For instance, in the case of a reversible double-color
thermal recording medium, an irreversible thermal composition comprising a basic achromatic dye (developing red
color) and an irreversible heat-resistant color developer as main components, an intermediate layer, and a reversible
thermal composition comprising a basic achromatic dye (developing black color) and a reversible heat-resistant color
developer as main components are laminated on the support in the order named. When heat energy is applied to the
reversible multi-color thermal recording medium by a thermal head, a color developing thermal reaction occurs in each
layer and a mixture of black and red colors, that is, reddish black color, is obtained. On the other hand, when this color
developing recording medium is subjected to heat treatment with a heated roll or thermal lamination, a decolorization
reaction is instantaneously caused by the basic achromatic dye (developing black color) and the reversible heat-resist-
ant color developer. As the result, red color developed by the irreversible thermal composition remains.
Further, as for color development and decolorization, a structural change (keto-enol tautomerism) represented by
the following formulae may occur in the urea and thiourea derivatives of the present invention depending on conditions.
It is considered that these compounds need to have an enol-form structure in order to function as color developers. To
cause keto-to-enol tautomerism, high temperatures obtained by a thermal head are required and, at the same time, tau-
tomerism to keto form occurs when an appropriate temperature and an appropriate amount of heat are given, resulting
in decolorization.
28
EP 0 709 225 B1
• N - C N
I II I
U Y II
( Keto-f orm)
-■ N - C = N -
^ t I
II Yfl
(Enol-form)
Y = (>. S
Meanwhile, when a red color developing thermal recording layer, an intermediate layer and a black color developing
thermal recording layer are laminated on the support in the order named, using conventional bisphenol A as a color
developer, a color developing thermal reaction occurs in each layer with heat energy applied by a thermal head, and
reddish black color, a mixture of black and red colors, is obtained. However, when this color developing recording
medium is subjected to heat treatment with a heated roll or to thermal lamination, the hue of image portions does not
change and reddish black color is markedly developed on the entire ground because bisphenol A is not a reversible
heat-resistant color developer.
The reason that the urea and thiourea derivatives which are heat-resistant color developers of the present invention
function as color developers for a dye precursor used in thermal recording media and optical recording media, the rea-
son that a thermal recording medium comprising a dye precursor and the color developer of the present invention exhib-
its extremely high heat resistance, and the reason that an optical recording medium comprising a dye precursor, the
color developer of the present invention and a light absorbent can undergo heat treatment with a heated roll or thermal
lamination and exhibits extremely high heat resistance are not elucidated yet, but can be considered as follows.
In the case of the above thermal recording, since a thermal head is instantaneously heated to a temperature of 200
to 300 °C , the urea and thiourea derivatives contained in the recording layer of the thermal recording medium which is
brought into contact with the thermal head undergo tautomerism to be converted into enol form and to exhibit a color
developing function. It is considered that the lactone ring of the dye precursor is thereby cleaved, with the result of color
development.
Further, in the case of the above optical recording, since a light absorbent is contained in the optical recording layer,
light irradiated from a recording light source is absorbed efficiently and converted into heat by this light absorbent. As
the temperature is elevated to 200 to 300 °C instantaneously at this point, the urea and thiourea derivatives contained
in the recording layer undergo tautomerism to be converted into enol form and to exhibit a color developing function, as
in the above thermal recording. It is considered that the lactone ring of the dye precursor is thereby cleaved with the
result of color development.
The urea and thiourea derivatives do not exhibit a color developing function at temperatures at which they do not
change into enol form. Since a reaction with the dye precursor does not occur, the color development of the background
does not take place. This seems to be the reason why heat resistance is high. The temperature at which the urea and
thiourea derivatives are converted into enol form is considered to be higher than a temperature required for heat treat-
ment with a heated roll and thermal lamination. For this reason, the color development of the ground does not take
place in high-temperature thermal environment such as heat treatment with a heated roll and thermal lamination.
Further, in the case of an optical recording medium structured above and subjected to thermal lamination, light irra-
diated from a recording light source transmits through a plastic film present on the optical recording layer, reaches the
light absorbent contained in the optical recording layer, and is converted into heat. Therefore, additional recording is
possible even after lamination.
Other and further objects, features and advantages of the invention will become clear from the following descrip-
tion.
The present invention is further illustrated with reference to the following examples. The term "parts" used herein
means "parts by weight".
29
EP 0 709 225 B1
(production of reversible multi-color thermal recording media: Examples 1 to 80 and Comparative Examples 1 to 10)
[Examples 1 to 20] [Examples V to 20']
Formation of irreversible thermal recording layer
Solution A (dispersion of irreversible heat-resistant color developer)
irreversible heat-resistance color developer (see Tables 1 and 1')
10% polyvinyl alcohol aqueous solution
water
6.0 parts
18.8 parts
11.2 parts
Solution B (dispersion of dye developing red color)
3,3-bis(1-ethyl-2-methylindole-3-yl)phthalide
2.0 parts
10% polyvinyl alcohol aqueous solution
4.6 parts
water
2.6 parts
The solutions having the above compositions were ground to an average particle diameter of 1 ^im with a sand
grinder. Subsequently, the resulting dispersions were mixed in the proportion below to prepare a thermal layer coating
fluid.
solution A
36.0 parts
solution B
9.2 parts
kaolin clay (50% dispersion)
12.0 parts
The above coating fluid was applied to one side of a 50 g/m 2 substrate in a coating weight of 5.0 g/m 2 . The coating
was then dried to form an irreversible thermal recording layer.
Formation of intermediate layer
kaolin clay (50% dispersion)
12.0 parts
10% polyvinyl alcohol aqueous solution
6.0 parts
water
3.0 parts
The solutions having the above compositions were mixed to prepare an intermediate layer coating fluid.
The intermediate layer coating fluid was applied to the above irreversible thermal recording layer in a coating weight
of 3.0 g/m 2 . The coating was then dried to form an intermediate layer.
30
EP 0 709 225 B1
Formation of reversible thermal recording layer
Solution D (dispersion of reversible heat-resistant color developer)
reversible heat-resistant color developer (see Tables 1 and 1')
1 0% polyvinyl alcohol aqueous solution
water
6.0 parts
18.8 parts
11.2 parts
Solution E (dispersion of dye developing black color)
3-n-dipentylamino-6-methyl-7-anilinofluoran
10% polyvinyl alcohol aqueous solution
water
2.0 parts
4.6 parts
2.6 parts
The solutions having the above compositions were ground to an average particle diameter of 1 jam with a sand
grinder. Subsequently, the resulting dispersions were mixed in the proportion below to prepare a thermal layer coating
fluid.
solution D
36.0 parts
solution E
9.2 parts
kaolin clay (50% dispersion)
1 2.0 parts
The above coating fluid was applied to the intermediate layer in a coating weight of 5.0 g/m 2 . The coating was then
dried to form a reversible thermal recording layer. This sheet was treated with a supercalender to achieve a smoothness
of 600 to 700 seconds so as to prepare a reversible multi-color thermal recording sheet.
[Examples 21 to 40] [Examples 21' to 40']
Formation of reversible thermal recording layer
Solution D (dispersion of reversible heat-resistant color developer)
reversible heat-resistant color developer (see Tables 2 and 2')
1 0% polyvinyl alcohol aqueous solution
water
6.0 parts
18.8 parts
11.2 parts
Solution E (dispersion of dye developing black color)
3-n-dipentylamino-6-methyl-7-anilinofluoran
2.0 parts
31
EP 0 709 225 B1
(continued)
10% polyvinyl alcohol aqueous solution
water
4.6 parts
2.6 parts
The solutions having the above compositions were ground to an average particle diameter of 1 jim with a sand
grinder. Subsequently, the resulting dispersions were mixed in the proportion below to prepare a thermal recording layer
coating fluid.
solution D
36.0 parts
solution E
9.2 parts
kaolin clay (50% dispersion)
12.0 parts
The above coating fluid was applied to one side of a 50 g/m 2 substrate in a coating weight of 5.0 g/m 2 . The coating
was then dried to form a reversible thermal recording layer.
Formation of intermediate layer
kaolin clay (50% dispersion)
12.0 parts
10% polyvinyl alcohol aqueous solution
6.0 parts
water
3.0 parts
The solutions having the above compositions were mixed to prepare an intermediate layer coating fluid.
The intermediate layer coating fluid was applied to the above reversible thermal recording layer in a coating weight
of 3.0 g/m 2 . The coating was then dried to form an intermediate layer.
Formation of irreversible thermal recording layer
Solution A (dispersion of irreversible heat-resistant color developer)
irreversible heat-resistant color developer (see Tables 2 and 2')
10% polyvinyl alcohol aqueous solution
water
6.0 parts
18.8 parts
1 1 .2 parts
Solution F (dispersion of dye developing blue color)
3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide
10% polyvinyl alcohol aqueous solution
water
2.0 parts
4.6 parts
2.6 parts
The solutions having the above compositions were ground to an average particle diameter of 1 with a sand
grinder. Subsequently the resulting dispersions were mixed in the proportion below to prepare a thermal recording layer
32
coating fluid.
EP 0 709 225 B1
solution A
36.0 parts
solution F
9.2 parts
kaolin clay (50% dispersion)
1 2.0 parts
The above coating fluid was applied to the intermediate layer in a coating weight of 5.0 g/m 2 . The coating was then
dried to form an irreversible thermal recording layer. This sheet was treated with a supercalender to achieve a smooth-
ness of 600 to 700 seconds so as to form a reversible multi-color thermal recording sheet.
[Comparative Examples 1 to 5]
Formation of thermal recording layer
Solution G (dispersion of conventional color developer)
conventional color developer (see Table 3)
6.0 parts
10% polyvinyl alcohol aqueous solution
18.8 parts
water
11.2 parts
Solution B (dispersion of dye developing red color)
3,3-bis(1-ethyl-2-methyl-indole-3-yl)phthalide
2.0 parts
10% polyvinyl alcohol aqueous solution
4.6 parts
water
2.6 parts
The solutions having the above compositions were ground to an average particle diameter of 1 urn with a sand
grinder. Subsequently, the resulting dispersions were mixed in the proportion below to prepare a thermal recording layer
coating fluid.
solution G
36.0 parts
solution B
9.2 parts
kaolin clay (50% dispersion)
1 2.0 parts
The above coating fluid was applied to one side of a 50 g/m 2 substrate in a coating weight of 5.0 g/m 2 . The coating
was then dried to form a thermal recording layer.
33
EP 0 709 225 B1
Formation of intermediate layer
kaolin clay (50% dispersion)
12.0 parts
10% polyvinyl alcohol aqueous solution
6.0 parts
water
3.0 parts
The solutions having the above compositions were mixed to prepare an intermediate layer coating fluid.
The intermediate layer coating fluid was applied to the above thermal recording layer in a coating weight of 3.0 g/m
2 . The coating was then dried to form an intermediate layer.
Formation of thermal recording layer
Solution H (dispersion of conventional color developer)
conventional color developer (see Table 3)
6.0 parts
10% polyvinyl alcohol aqueous solution
18.8 parts
water
1 1 .2 parts
Solution E (dispersion of dye developing black color)
3-n-dipentylamino-6-methyl-7-anilinofluoran
2.0 parts
10% polyvinyl alcohol aqueous solution
4.6 parts
water
2.6 parts
The solutions having the above compositions were ground to an average particle diameter of 1 jam with a sand
grinder. Subsequently the resulting dispersions were mixed in the proportion below to prepare a thermal recording layer
coating fluid.
solution H
36.0 parts
solution E
9.2 parts
kaolin clay (50% dispersion)
12.0 parts
The above coating fluid was applied to the intermediate layer in a coating weight of 5.0 g/m 2 . The coating was then
dried to form a thermal recording layer. This sheet was treated with a supercalender to achieve a smoothness of 600 to
700 seconds so as to prepare a thermal recording sheet.
A quality performance test was made on the thermal recording sheets obtained in the above Examples and Com-
parative Examples and results are shown in Tables 1 to 3.
Note (1) thermal recording: Using a printer for the Rupo-90FII personal wordprocessor (manufactured by Toshiba),
thermal recording was made on the reversible multi-color thermal recording media with the maximum application
energy (the same conditions were also employed for thermal recording shown below). The densities of image and back-
ground portions were measured by a Macbeth densitometer (RD-914 with an amber filter, the same conditions were
employed hereinafter). Developed color tones were determined visually.
34
EP 0 709 225 B1
Note (2) decolorization (by a heated roll): The reversible multi-color thermal recording media on which dynamic
recording was made by the method of Note (1 ) were fed through a roll heated to 1 1 5 °C at a speed of 7 mm/second and
the densities of image and ground portions were measured. As for the ground portions, the smaller the Macbeth density
values the more stable the color of the background portions becomes. Contrast between image and background por-
tions of a thermally recorded portion which was subjected to heat treatment with a heated roll was evaluated as follows.
Thermal recording media whose contrasts were rated A to X are difficult to read.
O no or almost no color development of background portions
A color development of background portions
X marked color development of background portions
Note (3) thermal recording: Using a printer for the Rupo-90FII wordprocessor (manufactured by Toshiba), thermal
recording was made on color undeveloped portions of reversible multi-color thermal recording media with the maximum
application energy after heat treatment with a heated roll. Developed color tones were determined visually.
35
EP 0 709 225 B1
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In Examples 1 to 20 and Examples 1' to 20', since a developed color tone changed from reddish black to red upon
erasure with a heated roll, the density of image portions lowered. However, stains were not observed in background
portions. The same tendency was observed in Examples 21 to 40. However, in Comparative Examples 1 to 5, there was
40
EP 0 709 225 B1
no change in the color tone of image portions upon erasure with a heated roll, color development occurred in all the
background portions, and additional thermal recording (3) could not be made because of the absence of color undevel-
oped portions.
[Examples 41 to 60] [Examples 41 ' to 60']
Formation of irreversible thermal recording layer
Solution A (dispersion of irreversible heat-resistant color developer)
irreversible heat-resistant color developer (see Tables 4 and 4')
10% polyvinyl alcohol aqueous solution
water
6.0 parts
18.8 parts
1 1 .2 parts
Solution I (dispersion of dye developing green color)
3-(N-p-tolyl-N-ethylamino)-7-(N-phenyl-N-methylamino)fluoran
10% polyvinyl alcohol aqueous solution
water
2.0 parts
4.6 parts
2.6 parts
The solutions having the above compositions were ground to an average particle diameter of 1 urn with a sand
grinder. Subsequently, the resulting dispersions were mixed in the proportion below to prepare a thermal recording layer
coating fluid.
solution I
36.0 parts
solution G
9.2 parts
kaolin clay (50% dispersion)
1 2.0 parts
The above coating fluid was applied to one side of a 50 g/m 2 substrate in a coating weight of 5.0 g/m 2 . The coating
was then dried to form an irreversible thermal recording layer.
Formation of intermediate layer
kaolin clay (50% dispersion)
12.0 parts
1 0% polyacrylamide emulsion
6.0 parts
water
3.0 parts
The solutions having the above compositions were mixed to prepare an intermediate layer coating fluid.
The intermediate layer coating fluid was applied to the above irreversible thermal recording layer in a coating weight
of 3.0 g/m 2 . The coating was then dried to form an intermediate layer.
41
EP 0 709 225 B1
Formation of reversible thermal recording layer
Solution D (dispersion of reversible heat-resistance color developer)
reversible heat-resistant color developer (see Tables 4 and 4')
10% polyvinyl alcohol aqueous solution
water
6.0 parts
18.8 parts
11.2 parts
Solution E (dispersion of dye developing black color)
3-n-dipentylamino-6-methyl-7-anilinofluoran
10% polyvinyl alcohol aqueous solution
water
2.0 parts
4.6 parts
2.6 parts
The solutions having the above compositions were ground to an average particle diameter of 1 jim with a sand
grinder. Subsequently, the resulting dispersions were mixed in the proportion below to prepare a thermal recording layer
coating fluid.
solution D
36.0 parts
solution E
9.2 parts
kaolin clay (50% dispersion)
12.0 parts
The above coating fluid was applied to the intermediate layer in a coating weight of 5.0 g/m 2 . The coating was then
dried to form a reversible thermal recording layer. This sheet was treated with a supercalender to achieve a smoothness
of 600 to 700 seconds so as to prepare a reversible multi-color thermal recording sheet.
[Examples 61 to 80] [Examples 6V to 80']
Formation of irreversible thermal recording layer
Solution A (dispersion of irreversible heat-resistant color developer)
irreversible heat-resistant color developer (see Tables 5 and 5')
10% polyvinyl alcohol aqueous solution
water
6.0 parts
18.8 parts
1 1 .2 parts
Solution J (dispersion of dye developing orange color)
3-cyclohexylamino-6-chlorofluoran
2.0 parts
42
EP 0 709 225 B1
(continued)
1 0% polyvinyl alcohol aqueous solution
water
4.6 parts
2.6 parts
The solutions having the above compositions were ground to an average particle diameter of 1 jam with a sand
grinder. Subsequently, the resulting dispersions were mixed in the proportion below to prepare a thermal recording layer
coating fluid.
solution A
36.0 parts
solution J
9.2 parts
kaolin clay (50% dispersion)
1 2.0 parts
The above coating fluid was applied to one side of a 50 g/m 2 substrate in a coating weight of 5.0 g/m 2 . The coating
was then dried to form an irreversible thermal recording layer.
Formation of intermediate layer
kaolin clay (50% dispersion)
12.0 parts
10% methyl polyacrylate emulsion
6.0 parts
water
3.0 parts
The solutions having the above compositions were mixed to prepare an intermediate layer coating fluid.
The intermediate layer coating fluid was applied to the above irreversible thermal recording layer in a coating weight
of 3.0 g/m 2 . The coating was then dried to form an intermediate layer.
Formation of reversible thermal recording layer
Solution D (dispersion of reversible heat-resistant color developer)
reversible heat-resistant color developer (see Tables 5 and 5')
1 0% polyvinyl alcohol aqueous solution
water
6.0 parts
18.8 parts
11.2 parts
Solution E (dispersion of dye developing black color)
3-n-dipentylamino-6-methyl-7-anilinofluoran
2.0 parts
10% polyvinyl alcohol aqueous solution
4.6 parts
water
2.6 parts
The solutions having the above compositions were ground to an average particle diameter of 1 with a sand
grinder. Subsequently, the resulting dispersions were mixed in the proportion below to prepare a thermal recording layer
43
coating fluid.
EP 0 709 225 B1
solution D
36.0 parts
solution E
9.2 parts
kaolin clay (50% dispersion)
12.0 parts
The above coating fluid was applied to the intermediate layer in a coating weight of 5.0 g/m 2 . The coating was then
dried to form a reversible thermal recording layer. This sheet was treated with a supercalender to achieve a smoothness
of 600 to 700 seconds so as to prepare a reversible multi-color thermal recording sheet.
[Comparative Examples 6 to 10]
Formation of thermal recording layer
Solution G (dispersion of conventional color developer)
conventional color developer (see Table 6)
6.0 parts
10% polyvinyl alcohol aqueous solution
18.8 parts
water
1 1 .2 parts
Solution I (dispersion of dye developing green color)
3-(N-p-tolyl-N-ethylamino)-7-(N-phenyl-N-methylamino)fluoran
10% polyvinyl alcohol aqueous solution
water
2.0 parts
4.6 parts
2.6 parts
The solutions having the above compositions were ground to an average particle diameter of 1 jam with a sand
grinder. Subsequently the resulting dispersions were mixed in the proportion below to prepare a thermal recording layer
coating fluid.
solution G
36.0 parts
solution I
9.2 parts
kaolin clay (50% dispersion)
12.0 parts
The above coating fluid was applied to one side of a 50 g/m 2 substrate in a coating weight of 5.0 g/m 2 . The coating
was then dried to form a thermal recording layer.
44
EP 0 709 225 B1
Formation of intermediate layer
kaolin clay (50% dispersion)
12.0 parts
1 0% polyacrylamide emulsion
6.0 parts
water
3.0 parts
The solutions having the above compositions were mixed to prepare an intermediate layer coating fluid.
The intermediate layer coating fluid was applied to the above thermal recording layer in a coating weight of 3.0 g/m
2 . The coating was then dried to form an intermediate layer. Formation of thermal recording layer
Solution G (dispersion of conventional color developer)
conventional color developer (see Table 6)
6.0 parts
10% polyvinyl alcohol aqueous solution
18.8 parts
water
11.2 parts
Solution E (dispersion of dye developing black color)
3-n-dipentylamino-6-methyl-7-anilinofluoran
2.0 parts
10% polyvinyl alcohol aqueous solution
4.6 parts
water
2.6 parts
The solutions having the above compositions were ground to an average particle diameter of 1 ^m with a sand
grinder. Subsequently, the resulting dispersions were mixed in the proportion below to prepare a thermal recording layer
coating fluid.
solution G
36.0 parts
solution E
9.2 parts
kaolin clay (50% dispersion)
1 2.0 parts
The above coating fluid was applied to the intermediate layer in a coating weight of 5.0 g/m ^ . The coating was then
dried to form a thermal recording layer. This sheet was treated with a supercalender to achieve a smoothness of 600 to
700 seconds so as to prepare a thermal recording sheet.
A quality performance test was made on the thermal recording sheets obtained in the above Examples and Com-
parative Examples and results are shown in Tables 4 to 6.
45
EP 0 709 225 B1
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Note (4) decolorization (by thermal lamination): A simplified lamination apparatus (MS Pouch H-140 manufactured
by Meiko Shokai K.K.) and a laminate film (MS Pouch Film MP1 0-6095) were used. A laminated thermal recording
50
EP 0 709 225 B1
medium having a thermal recording portion was fabricated by, sandwiching a reversible multi-color thermal recording
medium on which dynamic recording was made by the method of Note (1) between the above laminate films at a feed
rate of 20mm/sec. After thermal lamination, image and background portions which were subjected to the above thermal
recording were measured by a Macbeth densitometer through the laminate film of the laminated thermal recording
medium (high value cause of measurement through the laminate film). As for background portions, the smaller the Mac-
beth density value the more stable the color of the ground becomes. Contrast between image portions and background
portions of the laminated thermal recording portion was evaluated as follows. Laminated thermal recording media
whose contrasts are rated A to X are difficult to read. In fact, thermal lamination was impossible.
O no or almost no color development of the background portions (thermal lamination impossible)
A color development of the background portions
X marked color development of the background portions
In Examples 41 to 80 and Examples 41' to 80', thermal lamination was effected without failure and a change in the
color tone of image portions caused by thermal lamination was good. However, in Comparative Examples 6 to 10, there
was no change in the color tone of image portions caused by thermal lamination and color development occurred in all
the background portions.
( production of reversible multi-color optical recording medium, Examples 81 to 1 20, Examples 81 ' to 1 20' and Compar-
ative Examples 1 1 to 20 >
[Examples 81 to 100] [Examples 8V to 100]
Formation of irreversible optical recording layer
Solution A (dispersion of irreversible heat-resistant color developer)
irreversible heat-resistant color developer (see Tables 7 and 7')
10% polyvinyl alcohol aqueous solution
water
6.0 parts
18.8 parts
1 1 .2 parts
Solution B (dispersion of dye developing red color)
3,3-bis(1-ethyl-2-methylindole-3-yl)phthalide
2.0 parts
10% polyvinyl alcohol aqueous solution
4.6 parts
water
2.6 parts
Solution K (aqueous solution of light absorbent)
NK-2612 (manufactured by Nippon Kanko Shikiso Kenkyujo)
water
0.04 part
4.0 parts
The solutions having the above compositions were ground to an average particle diameter of 1 iim with a sand
grinder. Subsequently, the resulting dispersions were mixed in the proportion below to prepare an optical recording
layer coating fluid.
51
EP 0 709 225 B1
solution A
36.0 parts
solution B
9.2 parts
solution K
4.04 parts
kaolin clay (50% dispersion)
12.0 parts
The above coating fluid was applied to one side of a 50 g/m 2 substrate in a coating weight of 5.0 g/m 2 . The coating
was then dried to form an irreversible optical recording layer.
Formation of intermediate layer
kaolin clay (50% dispersion)
12.0 parts
10% polyvinyl alcohol aqueous solution
6.0 parts
water
3.0 parts
The solutions having the above compositions were mixed to prepare an intermediate layer coating fluid.
The intermediate layer coating fluid was applied to the above irreversible optical recording layer in a coating weight
of 3.0 g/m 2 . The coating was then dried to form an intermediate layer.
Formation of reversible optical recording layer
Solution D (dispersion of reversible heat-resistance color developer)
reversible heat-resistant color developer (see Tables 7 and 7)
10% polyvinyl alcohol aqueous solution
water
6.0 parts
18.8 parts
11.2 parts
Solution E (dispersion of dye developing black color)
3-n-dipentylamino-6-methyl-7-anilinofluoran
2.0 parts
10% polyvinyl alcohol aqueous solution
4.6 parts
water
2.6 parts
Solution K (aqueous solution of light absorbent)
NK-2612 (manufactured by Nippon Kanko Shikiso Kenkyujo)
water
0.04 part
4.0 parts
The solutions having the above compositions were ground to an average particle diameter of 1 jam with a sand
52
EP 0 709 225 B1
grinder. Subsequently, the resulting dispersions were mixed in the proportion below to prepare an optical recording
layer coating fluid.
solution D
36.0 parts
solution E
9.2 parts
solution K
4.04 parts
kaolin clay (50% dispersion)
12.0 parts
The above coating fluid was applied to the intermediate layer in a coating weight of 5.0 g/m 2 . The coating was then
dried to form a reversible optical recording layer. This sheet was treated with a supercalender to achieve a smoothness
of 600 to 700 seconds so as to prepare a reversible optical recording sheet.
[Comparative Examples 1 1 to 1 5]
Formation of optical recording layer
Solution G (dispersion of conventional color developer)
conventional color developer (see Table 8)
6.0 parts
10% polyvinyl alcohol aqueous solution
18.8 parts
water
11.2 parts
Solution B (dispersion of dye developing red color)
3,3-bis(1-ethyl-2-methyl-indole-3-yl)phthalide
2.0 parts
10% polyvinyl alcohol aqueous solution
4.6 parts
water
2.6 parts
Solution K (aqueous solution of light absorbent)
NK-2612 ((manufactured by Nippon Kanko Shikiso Kenkyujo)
water
0.04 part
4.0 parts
The solutions having the above compositions were ground to an average particle diameter of 1 jam with a sand
grinder. Subsequently, the resulting dispersions were mixed in the proportion below to prepare an optical recording
layer coating fluid.
solution G
36.0 parts
solution B
9.2 parts
53
EP 0 709 225 B1
(continued)
solution K
4.04 parts
kaolin clay (50% dispersion)
12.0 parts
The above coating fluid was applied to one side of a 50 g/m 2 substrate in a coating weight of 5.0 g/m 2 . The coating
was then dried to form an optical recording layer.
Formation of intermediate layer
kaolin clay (50% dispersion)
12.0 parts
10% polyvinyl alcohol aqueous solution
6.0 parts
water
3.0 parts
The solutions having the above compositions were mixed to prepare an intermediate layer coating fluid.
The intermediate layer coating fluid was applied to the above optical recording layer in a coating weight of 3.0 g/m
2 . The coating was then dried to form an intermediate layer.
Formation of optical recording layer
Solution G (dispersion of conventional color developer)
conventional color developer (see Table 8)
6.0 parts
10% polyvinyl alcohol aqueous solution
18.8 parts
water
1 1 .2 parts
Solution E (dispersion of dye developing black color)
3-n-dipentylamino-6-methyl-7-anilinofluoran
2.0 parts
10% polyvinyl alcohol aqueous solution
4.6 parts
water
2.6 parts
Solution K (aqueous solution of light absorbent)
NK-2612 ((manufactured by Nippon Kanko Shikiso Kenkyujo)
water
0.04 part
4.0 parts
The solutions having the above compositions were ground to an average particle diameter of 1 ^m with a sand
grinder. Subsequently, the resulting dispersions were mixed in the proportion below to prepare an optical recording
layer coating fluid.
54
EP 0 709 225 B1
solution G
36.0 parts
solution E
9.2 parts
solution K
4.04 parts
kaolin clay (50% dispersion)
12.0 parts
The above coating fluid was applied to the intermediate layer in a coating weight of 5.0 g/m 2 . The coating was then
dried to form an optical recording layer. This sheet was treated with a supercalender to achieve a smoothness of 600
to 700 seconds so as to prepare an optical recording sheet.
[Examples 101 to 120] [Examples 101' to 120']
Formation of irreversible optical recording layer
Solution L (simultaneous dispersion of irreversible heat-resistant color developer and light absorbent)
irreversible heat-resistant color developer (see Tables 9 and 9') 6.0 parts
bis(1 -tert-butyl-3,4-dithiophenolate)nickeltetra-n-butylammonium (light absorbent) 0.3 part
10% polyvinyl alcohol aqueous solution 18.8 parts
water 11.2 parts
Solution F (dispersion of dye developing blue color)
3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide
10% polyvinyl alcohol aqueous solution
water
2.0 parts
4.6 parts
2.6 parts
The solutions having the above compositions were ground to an average particle diameter of 1 ^m with a sand
grinder. Subsequently, the resulting dispersions were mixed in the proportion below to prepare an optical recording
layer coating fluid.
solution L
36.3 parts
solution F
9.2 parts
kaolin clay (50% dispersion)
1 2.0 parts
The above coating fluid was applied to one side of a 50 g/m 2 substrate in a coating weight of 5.0 g/m 2 . The coating
was then dried to form an irreversible optical recording layer.
55
EP 0 709 225 B1
Formation of intermediate layer
kaolin clay (50% dispersion)
12.0 parts
10% polyacrylamide emulsion
6.0 parts
water
3.0 parts
The solutions having the above compositions were mixed to prepare an intermediate layer coating fluid.
The intermediate coating fluid was applied to the above irreversible optical recording layer in a coating weight of 3.0
g/m 2 . The coating was then dried to form an intermediate layer.
Formation of reversible optical recording layer
Solution M (simultaneous dispersion of reversible heat-resistant color developer and light absorbent)
reversible heat-resistant color developer (see Table 9) 6.0 parts
bis(1 -tert-butyl-3,4-dithiophenolate)nickeltetra-n-butylammonium (light absorbent) 0.3 part
1 0% polyvinyl alcohol aqueous solution 1 8.8 parts
water 11.2 parts
Solution E (dispersion of dye developing black color)
3-n-dipentylamino-6-methyl-7-anilinofluoran
2.0 parts
10% polyvinyl alcohol aqueous solution
4.6 parts
water
2.6 parts
The solutions having the above compositions were ground to an average particle diameter of 1 jam with a sand
grinder. Subsequently, the resulting dispersions were mixed in the proportion below to prepare a thermal recording layer
coating fluid.
solution M
36.3 parts
solution E
9.2 parts
kaolin clay (50% dispersion)
12.0 parts
The above coating fluid was applied to the intermediate layer in a coating weight of 3.0 g/m * . The coating was then
dried to form a reversible optical recording layer. This sheet was treated with a supercalender to achieve a smoothness
of 600 to 700 seconds to prepare a reversible multi-color optical recording sheet.
56
EP 0 709 225 B1
[Comparative Examples 16 to 20]
Formation of optical recording layer
Solution N (simultaneous dispersion of conventional color developer and light absorbent)
conventional color developer (see Table 1 0) 6.0 parts
bis(1 -tert-butyl-3,4-dithiophenolate)nickeltetra-n-butylammonium (light absorbent) 0.3 part
1 0% polyvinyl alcohol aqueous solution 1 8.8 parts
water 11.2 parts
Solution F (dispersion of dye developing blue color)
3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide
10% polyvinyl alcohol aqueous solution
water
2.0 parts
4.6 parts
2.6 parts
The solutions having the above compositions were ground to an average particle diameter of 1 jam with a sand
grinder. Subsequently, the resulting dispersions were mixed in the proportion below to prepare an optical recording
layer coating fluid.
solution N
36.3 parts
solution F
9.2 parts
kaolin clay (50% dispersion)
1 2.0 parts
The above coating fluid was applied to one side of a 50 g/m 2 substrate in a coating weight of 5.0 g/m 2 . The coating
was then dried to form an optical recording layer.
Formation of intermediate layer
kaolin clay (50% dispersion)
12.0 parts
1 0% polyacrylamide emulsion
6.0 parts
water
3.0 parts
The solutions having the above compositions were mixed to prepare an intermediate layer coating fluid.
The intermediate layer coating fluid was applied to the above optical recording layer in a coating weight of 3.0 g/m
. The coating was then dried to form an intermediate layer.
57
EP 0 709 225 B1
Formation of optical recording layer
Solution O (simultaneous dispersion of conventional color developer and light absorbent)
conventional color developer (see Table 10) 6.0 parts
bis(1 -tert-butyl-3,4-dithiophenolate)nickeltetra-n-butylammonium (light absorbent) 0.3 part
1 0% polyvinyl alcohol aqueous solution 1 8.8 parts
water 11.2 parts
Solution E (dispersion of dye developing black color)
3-dipentylamino-6-methyl-7-anilinofluoran
10% polyvinyl alcohol aqueous solution
water
2.0 parts
4.6 parts
2.6 parts
The solutions having the above compositions were ground to an average particle diameter of 1 jam with a sand
grinder. Subsequently, the resulting dispersions were mixed in the proportion below to prepare an optical recording
layer coating fluid.
solution O
36.3 parts
solution E
9.2 parts
kaolin clay (50% dispersion)
12.0 parts
The above coating fluid was applied to the intermediate layer in a coating weight of 5.0 g/m 2 . The coating was then
dried to form an optical recording layer. This sheet was treated with a supercalender to achieve a smoothness of 600
to 700 seconds to prepare an optical recording sheet.
A quality performance test was made on the optical recording sheets obtained in the above Examples and Com-
parative Examples and results are shown in Tables 7 to 10.
58
EP 0 709 225 B1
additional
optical
recording (7)
Color
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EP 0 709 225 B1
additional
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EP 0 709 225 B1
additional
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recordina (7)
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-H rH
(0 (U
H rH
> Cr%
-H rH
*J
(0 OJ
H rH
Pi e
3 S
Note (5) optical recording: Using a laser plotter disclosed in Japanese Patent Publication No. 3-239598, laser
recording was carried out by the following method. The LT01 5MD semiconductor laser (manufactured by Sharp) having
an oscillation wavelength of 830 nm and an output of 30 mW was used as a light source for optical recording, and two
64
EP 0 709 225 B1
of the AP4545 non-spherical plastic lens (manufactured by Konica) having an aperture of 0.45 and a focusing distance
of 4.5 mm were used as condenser lenses. A laser recording head comprising the above semiconductor laser and
lenses was caused to scan at a recording speed of 50 mm/sec and at recording line intervals of 50 to obtain a 1
cm2 solid-colored image. This 1 cm 2 solid-colored image was measured for its density with a Macbeth densitometer
(RD-914 using an amber filter). This value was taken as the optical recording density of image portions. The reason why
the values of background portions are slightly bad in Examples 81 to 120 is that the optical recording media are slightly
colored because of the colored light absorbent. In Comparative Examples 1 1 to 20, decolorization was not caused by
thermal lamination and, conversely, marked color development occurred in the ground portions. As the result, additional
recording could not be carried out.
Note (6) decolorization (by thermal lamination): A simplified lamination apparatus (MS Pouch H-140 manufactured
by Meiko Shokai K.K.) and a laminate film (MS Pouch Film MP1 0-6095) were used. A laminated optical recording
medium having a thermal recording portion was fabricated by sandwiching a reversible multi-color optical recording
medium on which optical recording was made by the method of Note (4) between the above laminate films at a feed
rate of 20 mm/sec. After thermal lamination, image and background portions which were subjected to the above optical
recording were measured by a Macbeth densitometer through the laminate film of the laminated optical recording
medium (high value because of measurement through the laminate film). As for background portions, the smaller the
Macbeth density value the more stable the color of the background becomes. Contrast between image portions and
background portions of the laminated thermal recording portion was evaluated as follows. Laminated optical recording
media whose contrasts are rated A to X are difficult to read. In fact, thermal lamination was impossible.
O no or almost no color development of the ground portions (thermal lamination possible)
A color development of the ground portions
X marked color development of the ground portions
Note (7) additional recording: Optical recording was made on optical recording media after thermal lamination by
the following method, using flash light from a strobe. Optical recording was effected by stopping down the window of the
auto 4330 strobe flash for cameras (manufactured by Sunpack Co.) to 5% and irradiating light. The color developed
images were measured for their densities by a Macbeth densitometer (RD-914 using an amber filter). The density val-
ues were taken as optical recording densities of the image portions.
In Examples 81 to 120, thermal lamination was carried out after optical recording without failure, a change in the
color tone of the image portions caused by thermal lamination was good, and there were no stains in the ground por-
tions. However, in Comparative Examples 1 1 to 20, there was no change in the color tone of the image portions caused
by thermal lamination and color development occurred in all the ground portions. Therefore, additional optical recording
(7) could not be carried out.
As described on the foregoing pages, the reversible multi-color thermal recording medium and reversible multi-
color optical recording medium of the present invention which use urea and thiourea derivatives as a reversible heat-
resistant color developer and irreversible heat-resistant color developer cause almost no fogging of a background color
under temperature environment of up to 160 °C and recording of an image having a vivid color tone and many practical
applications is easily effected with a thermal recording apparatus such as a thermal head and an optical recording
apparatus using a laser or strobe. Therefore, the present invention has the following effects.
(1) A reversible multi-color thermal recording medium and a reversible multi-color optical recording medium provid-
ing a vivid color tone can be obtained.
(2) The reversible multi-color thermal recording medium and the reversible multi-color optical recording medium
can be used under extreme temperature conditions (90 to 160 °C, for example) under which conventional recording
media cannot be used.
(3) Since the reversible multi-color thermal recording medium and reversible multi-color optical recording medium
which have recorded images can undergo thermal lamination with a laminator, reversible multi-color thermal
recording cards and reversible multi-color optical recording cards can be fabricated with ease.
(4) Additional optical recording can be made on a laminated reversible multi-color optical recording medium.
(5) Since the ground colors of the reversible multi-color thermal recording medium and reversible multi-color optical
recording medium are stable even if they were fed through a heated roll, they can be used as paper for electronic
photocopiers.
Further, in the present invention, since the hue of an image obtained by first recording or erasure is made different
from that of an image recorded next by combining a reversible recording composition and an irreversible recording com-
position, it is possible to find whether or not a recorded image is recorded additionally, thus making it usable for preven-
tion of forgeries.
65
EP 0 709 225 B1
Claims
1. A reversible multi-color thermal recording medium which comprises, laminated on a substrate:
(i) an irreversible thermal composition comprising a colorless or pale basic achromatic dye and an organic irre-
versible heat-resistant color developer; and
(ii) a reversible thermal composition comprising a colorless or pale basic achromatic dye and an organic
reversible heat-resistant color developer.
2. A recording medium according to claim 1, which further comprises an intermediate layer interposed between
recording layers which comprise the thermal compositions (i) and (ii).
3. A recording medium according to claim 1 or 2, wherein the reversible heat-resistant color developer has the follow-
ing formula (I):
o o
NH-C-NH-(CH 2 ) m -NH-C-NH-^( )> ( I )
wherein X is selected from hydrogen, C-|-C 12 alkyl, halo-C-|-C 3 alkyl, C-|-C 12 alkoxy, C-|-C 12 alkoxycarbonyl,
C-|-C 12 acyl, C r C 12 dialkylamino, nitro, cyano and halogen, m is an integer of 1 to 12 and n is an integer of 1 to 3;
or the following general formula (I'):
o
R-NH-C-NH-/r 4^0H (V)
wherein R is C 12 -C 22 alkyl, A is selected from lower alkyl, lower alkoxy, lower alkoxycarbonyl, nitro, halogen
and hydrogen, and n is an integer of 1 to 3.
4. A recording medium according to any one of claims 1 to 3 wherein the irreversible heat-resistant color developer
has a formula selected from the following formulae (II), (III), (IV) and (V):
S0 2 -NH 2 ( II )
wherein X is selected from C1-C4 alkyl, C1-C3 alkoxy hydrogen, nitro, cyano and halogen, and m is an inte-
ger of 1 to 3:
66
EP 0 709 225 B1
NH-C-NH
(III)
10
15
wherein each of X, R-,, R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 , which are the same or different, is independently
selected from C r C 6 alkyl, C^-Cq alkoxy, hydrogen, nitro, cyano and halogen, and m is an integer of 1 to 3;
20
o o
n u
NH-C-NH— (CH 2 ) m -NH-C-
(IV)
25
wherein X is selected from C|-C 6 alkyl, C-|-C 6 alkoxy nitro, halogen and hydrogen, m is an integer of 1 to 12
and n is 1 or 2;
30
o
NH-C-NH
(V)
35
wherein X is selected from C1-C12 alkyl, C1-C12 alkoxy, trihalomethyl, hydrogen, nitro and halogen, Z is
selected from O, S, straight chain C1-C12 alkylene, branched chain C^C-^ alkylene, NH, S0 2 and C=0, each of
R 1 , R 2 and R 3 , which are the same or different, is independently selected from C 1 -C 6 alkyl, hydrogen, nitro and hal-
ogen, and n is an integer of 1 to 3.
40
5. A reversible multi-color thermal recording medium obtainable by laminating a plastic film on a recording medium as
defined in any one of the preceding claims, either on the recording surface thereof or on the entire recording
medium after thermal recording has occurred.
45 6. A reversible multi-color optical recording medium which comprises, in a recording layer of a recording medium as
defined in any one of claims 1 to 4, a light absorbent for absorbing light and converting it into heat.
7. An optical recording medium obtainable by laminating a plastic film on a reversible multi-color optical recording
medium as defined in claim 6, either on the recording surface thereof or on the entire recording medium.
50
8. An optical recording medium obtainable by laminating a plastic film on a reversible multi-color optical recording
medium as defined in claim 6, either on the recording surface thereof or on the entire recording medium after ther-
mal recording or optical recording has occurred.
55 9. A method of optical recording, which method comprises applying flash light from a stroboscope or laser light to an
optical recording medium as defined in claim 7 or 8.
1 0. A sheet suitable for an electronic photocopier, which comprises a recording medium as defined in any one of claims
67
EP 0 709 225 B1
1 to 4 or an optical recording medium as defined in claim 6.
Patentanspruche
1. Reversibles thermisches Mehrfarben-Aufzeichnungsmedium, das, laminiert auf ein Substrat, umfaBt:
(i) eine irreversible thermische Zusammensetzung, umfassend einen farblosen oder blassen, basischen achro-
matischen Farbstoff und einen organischen, irreversiblen, hitzebestandigen Farbentwickler; und
(ii) eine reversible thermische Zusammensetzung, umfassend einen farblosen oder blassen basischen, achro-
matischen Farbstoff und einen organischen, reversiblen, warmebestandigen Farbentwickler.
2. Aufzeichnungsmedium nach Anspruch 1, weiterhin eine zwischen den Aufzeichnungsschichten, die die thermi-
schen Zusammensetzungen (i) und (ii) umfassen, angeordnete Zwischenschicht umfassend.
3. Aufzeichnungsmedium nach Anspruch 1 oder 2, wobei der reversible, warmebestandige Farbentwickler die fol-
gende Formel (I) besitzt:
o o
)V— NH-C-NH— (CH^m-NH-C-NH
(I)
worin X ausgewahlt ist aus Wasserstoff, C-| bis C 12 Alkyl, Halogen C-| bis C 3 Alkyl, C-| bis C 12 Alkoxy, Ci bis C 12
Alkoxycarbonyl, C-| bis C-| 2 Acyl, C-| bis C-| 2 Dialkylamino, Nitro, Cyano, und Halogen, m eineganze Zahl von 1 bis
12 ist und n eine ganze Zahl von 1 bis 3; oder die folgende allgemeine Formel (I'):
o
R-NH-C-NH
(!')
worin R C 12 bis C 22 Alkyl ist, A ausgewahlt aus Niederalkyl, Niederalkoxy, Niederalkoxycarbonyl, Nitro, Halogen
und Wasserstoff und n eine ganze Zahl von 1 bis 3 ist.
4. Aufzeichnungsmedium nach einem der Anspruche 1 bis 3, wobei der irreversible, warmebestandige Farbentwickler
eine aus den folgenden Formeln (II), (III), (IV) und (V) ausgewahlte Struktur besitzt:
worin X ausgewahlt ist aus Ci bis C 4 Alkyl, Ci bis C 3 Alkoxy, Wasserstoff, Nitro, Cyano und Halogen, und m eine
ganze Zahl von 1 bis 3 ist.
68
EP 0 709 225 B1
worin jeder von X, , R 2 , R3, R4, R5, R6. R7 und R 8 , die dieselben oder verschieden sind, unabhangig ausgewahlt
ist aus C-| bis C 6 Alkyl, C-| bis C 6 Alkoxy, Wasserstoff, Nitro, Cyano und Halogen, und m eine ganze Zahl von 1 bis
3 ist;
worin X ausgewahlt ist aus C-| bis C 6 Alkyl, C-| bis C 6 Alkoxy, Nitro, Halogen und Wasserstoff, m eine ganze Zahl
von 1 bis 12 ist und n 1 oder 2;
R1
worin X ausgewahlt ist aus C1 bis C 12 Alkyl, bis C 12 Alkoxy, Trihalomethyl, Wasserstoff, Nitro und Halogen, Z
ausgewahlt ist aus O, S, gradkettigem C 1 bis C 12 Alkylen, verzweigtem C 1 bis C 12 Alkylen, NH P S0 2 und C=0,
wobei jeder von R-j , R 2 und R 3 , die dieselben oder verschieden sein konnen, unabhangig ausgewahlt ist aus C1 bis
C 6 Alkyl, Wasserstoff, Nitro und Halogen, und n eine ganze Zahl von 1 bis 3 ist.
Reversibles, mehrfarbiges thermisches Aufzeichnungsmedium, erhaltlich durch Laminieren eines Kunststoffilms
auf ein Aufzeichnungsmedium wie in einem der vorhergehenden Anspruche definiert, entweder auf dessen Auf-
zeichnungsoberflache oder auf das gesamte Aufzeichnungsmedium nachdem die thermische Aufzeichnung erfolgt
ist.
Reversibles, mehrfarbiges optisches Mehrfarben-Aufzeichnungsmedium, das, in einer Aufzeichnungsschicht eines
Aufzeichnungsmediums wie in einem der Anspruche 1 bis 4 definiert, ein Lichtabsorbens zur Absorption von Licht
und dessen Umwandlung in Warme umfaBt.
Optisches Aufzeichnungsmedium, erhaltlich durch Laminieren eines Kunststoffilms auf ein reversibles, optisches
Mehrfarben-Aufzeichnungsmedium wie in Anspruch 6 definiert, entweder auf dessen Aufzeichnungsoberflache
oder auf dem gesamten Aufzeichnungsmedium.
Optisches Aufzeichnungsmedium, erhaltlich durch Laminieren eines Kunststoffilms auf ein reversibles, optisches
Mehrfarben-Aufzeichnungsmedium, wie in Anspruch 6 definiert, entweder auf dessen Aufzeichnungsoberflache
oder auf dem gesamten Aufzeichnungsmedium nachdem eine thermische Aufzeichnung oder optische Aufzeich-
nung erfolgt ist.
69
EP 0 709 225 B1
9. Verfahren zur optischen Aufzeichnung, umfassend die Anwendung von Blitzlicht von einem Stroboskop oder Laser-
licht auf ein optisches Aufzeichnungsmedium, wie in Anspruch 7 oder 8 definiert.
10. Fur einen elektronischen Fotokopierer geeignetes Blatt, das ein Aufzeichnungsmedium, wie in einem der Anspru-
che 1 bis 4 definiert oder ein optisches Aufzeichnungsmedium wie in Anspruch 6 definiert umfaBt.
Revendications
1. Support d'enregistrement thermique polychrome reversible, qui comprend, stratifiees sur un substrat :
(i) une composition thermique irreversible comprenant un colorant achromatique de base incolore ou pale et
un developpeur de couleur thermoresistant irreversible organique ; et
(ii) une composition thermique reversible comprenant un colorant achromatique de base incolore ou pale et un
developpeur de couleur thermoresistant reversible organique.
2. Support d'enregistrement selon la revendication 1 , qui comprend en outre une couche intermediate interposee
entredes couches d'enregistrement qui contiennent les compositions thermiques (i) et (ii).
3. Support d'enregistrement selon la revendication 1 ou la revendication 2, dans lequel le developpeur de couleur
thermoresistant reversible a la formule (I) suivante :
O O
NH-—C— NH — (CHJm - NH—C— NH — (( )> ( I )
dans laquelle X est choisi parmi I'hydrogene, un alcoyle en C-|-C 12 , un haloalcoyle en C-|-C 3 , un alcoxy en C-|-C 12 ,
un alcoxycarbonyle en C-|-Ci 2 , un acyle en C-|-Ci 2 , un dialcoylamino en C-|-C-| 2 , un nitro, un cyano et un halogene,
m est un entier de 1 a 1 2 et n est un entier de 1 a 3 ;
ou la formule generale (I') suivante :
o
R-NH-C-NH-^f 4V-OH ( V )
dans laquelle R est un alcoyle en C-| 2 -C 22 , A est choisi parmi un alcoyle inferieur, un alcoxy inferieur, un alcoxycar-
bonyle inferieur, un nitro, un halogene et un hydrogene, et n est un entier de 1 a 3.
4. Support d'enregistrement selon Tune quelconque des revendications 1 a 3, dans lequel le developpeur de couleur
thermoresistant irreversible a une formule choisie parmi les formules (II), (III), (IV) et (V) suivantes :
I I! j
H O H
Xm \0/ 7"^r~ f i ^(3-so 2 -nh 2 ( II )
dans laquelle X est choisi parmi un alcoyle en C1-C4, un alcoxy en C1-C3, un hydrogene, un nitro, un cyano et un
halogene, et m est un entier de 1 a 3 ;
70
EP 0 709 225 B1
5
(!")
10
dans laquelle X, Ri, R 2 , R3, R4, R5, R6, R7 et Rq, qui sont identiques ou differents, sont choisis chacun indepen-
damment parmi un alcoyle en C-|-C 6l un alcoxy en C-|-C 6l un hydrogene, un nitro, un cyano et un halogene, et m
est un entier de 1 a 3 ;
15
NH-C-NH—(CH 2 ) m -NH-C-NH^(^n ( IV )
HO
20
dans laquelle X est choisi parmi un alcoyle en Ci-C 6 , un alcoxy en Ci-C 6 , un nitro, un halogene et un hydrogene,
m est un entier de 1 a 12 et n est egal a 1 ou 2 ;
25
Ri
dans laquelle X est choisi parmi un alcoyle en C-|-C-| 2 , un alcoxy en C-|-C 12 , un trihalomethyle, un hydrogene, un
nitro et un halogene, Z est choisi parmi O, S, un alcoylene en C1-C12 a chatne droite, un alcoylene en Ci-C 12 a
35 chaine ramifiee, NH, S0 2 et C=0, R-i, R 2 et R 3 , qui sont identiques ou differents, sont choisis chacun independam-
ment parmi un alcoyle en C-|-C 6 , un hydrogene, un nitro et un halogene, et n est un entier de 1 a 3.
5. Support d'enregistrement thermique polychrome reversible obtenu en stratifiant un film plastique sur un support
d'enregistrement selon Tune quelconque des revendications precedentes, soit sur sa surface d'enregistrement, soit
40 sur le support d'enregistrement tout entier, apres I'enregistrement thermique.
6. Support d'enregistrement optique polychrome reversible, qui comprend, dans une couche d'enregistrement d'un
support d'enregistrement selon I'une quelconque des revendications 1 a 4, un absorbant de la lumiere pour absor-
ber la lumiere et la convertir en chaleur.
45
7. Support d'enregistrement optique pouvant etre obtenu en stratifiant un film plastique sur un support d'enregistre-
ment optique polychrome reversible selon la revendication 6, soit sur sa surface d'enregistrement, soit sur le sup-
port d'enregistrement tout entier.
so 8. Support d'enregistrement optique pouvant etre obtenu en stratifiant un film plastique sur un support d'enregistre-
ment optique polychrome reversible selon la revendication 6, soit sur sa surface d'enregistrement, soit sur le sup-
port d'enregistrement tout entier, apres enregistrement thermique ou enregistrement optique.
9. Procede d'enregistrement optique, lequel procede comprend I'etape dans laquelle on applique une lumiere a eclats
55 en provenance d'un stroboscope, ou une lumiere laser a un support d'enregistrement optique selon la revendica-
tion 7 ou la revendication 8.
10. Feuille appropriee pour un photocopieur electronique, qui comprend un support d'enregistrement selon I'une quel-
71
EP 0 709 225 B1
conque des revendications 1 a 4, ou un support d'enregistrement optique selon la revendication 6.
5
10
15
20
25
30
35
40
45
50
72
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